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[[File:Indroda eggs.JPG|thumb|160px|Fossilized [[sauropod]] eggs displayed at [[Indroda Dinosaur and Fossil Park]]]]
'''Dinosaur eggs''' are the organic vessels in which a [[dinosaurs|dinosaur]] embryo develops. When the first scientifically documented remains of non-avian dinosaurs were being described in [[England]] during the 1820s, it was presumed that dinosaurs had laid [[egg (biology)|eggs]] because they were [[reptiles]].<ref name="enbd-first-1" /> In 1859, the first scientifically documented dinosaur egg fossils were discovered in [[France]] by Jean-Jacques Poech, although they were mistaken for giant [[bird eggs]] ([[birds]] were not yet recognized as dinosaurs at the time).
The first scientifically recognized non-avian dinosaur egg fossils were discovered in 1923 by an [[American Museum of Natural History]] crew in [[Mongolia]]. Dinosaur eggshell can be studied in [[thin section]] and viewed under a [[microscope]]. The interior of a dinosaur egg can be studied using [[CAT scans]] or by gradually dissolving away the shell with [[acid]]. Sometimes the egg preserves the remains of the developing [[embryo]] inside. The oldest known dinosaur eggs and embryos are from ''[[Massospondylus]]'', which lived during the [[Early Jurassic]], about 190 million years ago.<ref name="skinner">Skinner, Justin.[http://www.insidetoronto.com/news/local/article/812684--rom-puts-oldest-dinosaur-eggs-ever-discovered-on-display "ROM Puts Oldest Dinosaur Eggs Ever Discovered on Display"]. insidetoronto.com. May 6, 2010.</ref><ref name="moskovitch">Moskvitch, Katia. [https://www.bbc.co.uk/news/science-environment-11734616 "Eggs with the Oldest Known Embryos of a Dinosaur Found"]. BBC News. November 12, 2010.</ref>
==History==
{{Main|Timeline of egg fossil research}}
[[File:Citipati embryo.jpg|thumb|A ''[[Citipati (dinosaur)|Citipati]] osmolskae'' egg with preserved embryo, at the [[American Museum of Natural History|AMNH]].]]
In 1859, the first scientifically documented dinosaur egg fossils were discovered in southern France by a [[Catholic priest]] and amateur naturalist named Father [[Jean-Jacques Pouech]]; he thought, however, that they were laid by giant birds.<ref name="enbd-first-5">"First Discoveries," Carpenter (1999); page 5.</ref> The first scientifically recognized dinosaur egg fossils were discovered [[serendipitously]] in 1923 by an [[American Museum of Natural History]] crew while looking for evidence of [[early humans]] in Mongolia.<ref name="enbd-first-4">"First Discoveries," Carpenter (1999); page 4.</ref> These eggs were mistakenly attributed to the locally abundant herbivore ''[[Protoceratops]]'', but are now known to be ''[[Oviraptor]]'' eggs. Egg discoveries continued to mount all over the world, leading to the development of multiple competing classification schemes.
==Identification==
Fossil dinosaur eggshell fragments can be recognized based on three important traits. Their thickness should be roughly uniform, they are usually slightly curved, and their surface is covered in tiny pores. Less frequently, the [[wikt:concave|concave]] underside of the eggshell fragment will preserve bumps known as [[mammillae]]. Sometimes the embryo had absorbed so much of the calcium that the mammilae need a magnifying glass or [[microscope]] to be seen.<ref name="enbd-collecting-115" /> However, there are many kinds of naturally occurring objects which can resemble fossil eggs. These can fool even professional paleontologists.<ref name="enbd-fake-118" />
[[File:Zkamenělé vejce dinosaura z pouště Gobi, expozice Národního muzea v Praze (2007).jpg|thumb|left|Fossilized dinosaur egg from the Gobi desert, National Museum in Prague]]
===False eggs===
'''Calculus:''' Calculi are egg-like objects formed in the stomachs of [[ruminants]] such as [[cattle]], [[deer]], [[elk]], and [[goats]]. Calculus formation is a defense mechanism protecting the ruminant's stomach from damage if it swallows a foreign object while grazing. After ingestion, the object is covered by the same material composing bone, [[calcium phosphate]], and eventually vomited out of the animal's system. These "stomach stones" tend to range in size from 1 to 6 centimeters. Larger sizes are known but very rare.<ref name="enbd-fake-121" /> Sometimes tiny dimples cover the surface of a stomach stone, which can fool observers into thinking they are the pores of an egg.<ref name="enbd-fake-120" /> Fossil egg expert Ken Carpenter has described stomach stones as the most egg-like natural objects, noting that they are "the trickiest [egg-like] objects to correctly identify".<ref name="enbd-fake-120-121" /> Calculi are so egg-like that on one occasion a detailed description of a stomach stone misidentified as a fossil egg was published in the scientific literature.<ref name="enbd-fake-120" /> Calculi can be distinguished from real egg fossils because when they are broken open, they show the layers of calcium phosphate and the foreign object at the core.<ref name="enbd-fake-120" /> Multiple layers of eggshell are known in [[Egg paleopathology|pathological eggs]], but these layers don't go all the way down to its core the way a stomach stone's do. Calculi are often suspiciously intact, unlike fossil eggs, which are usually damaged.<ref name="enbd-fake-121" /> Stomach stones also lack distinct shells with their attending structural components like continuous or prismatic layers, mammillae, and pores.<ref name="enbd-fake-120" />
'''Concretions:''' [[Concretions]] are formed when decaying organisms change the chemistry of their immediate surroundings in a manner that is conducive to minerals [[precipitating]] out of solution. These minerals accumulate in a mass roughly shaped like the region of altered chemistry. Sometimes the {{Not a typo|mass produced}} is egg-shaped.<ref name="enbd-fake-119" /> Most egg-shaped concretions have uniform interiors, however some form through the accumulation of mineral in layers.<ref name="enbd-fake-119-120" /> These layered concretions can be even harder to recognize than those with uniform interiors because the layers can resemble egg white and yolk. The yellow of the false yolk comes from minerals like limonite, siderite, and sulfur.<ref name="enbd-fake-120" />
Concretions also generally lack distinct shells, although sometimes they can appear to have them if their outside surfaces have been case-hardened. Since their interiors are softer, erosion can separate the two, creating eggshell pseudofossils. Real egg fossils should preserve eggshell structures like pores, mammillae, and prismatic or continuous layers, which are not present in concretions. Any given concretion is unlikely to be exactly the same size as any other, so associations of egg-like objects of different sizes are probably not real eggs at all. Concretions can also be far larger than any real egg so an apparently unnaturally large "egg" has probably been misidentified.<ref name="enbd-fake-120" />
'''Insect trace fossils:''' Sometimes the living or breeding chambers of an insect burrow are so perfectly egg-shaped that even a paleontologist can mistake a natural cast of these chambers for a fossil egg. Insect burrow fossils can sometimes be distinguished from real egg fossils by the presence of "scratch marks" on their surface left by the insect during the burrow's original excavation. Fossil insect pupae can also resemble eggs. After death and burial, the decomposition of a deceased pupa would leave a gap in the sediment that could be filled with minerals carried by groundwater, forming an egg-like cast. These pseudo-eggs can be recognized by their small size (usually not much longer than a centimeter or two) and lack of an eggshell with its typical anatomy.<ref name="enbd-fake-120" />
'''Stones:''' The erosive effects of water can sometimes round rocks into egg-like shapes.<ref name="enbd-fake-119" />
==Structure==
Paleontologists' knowledge of the structure of dinosaur eggs is limited to the hard shell. However, it can be inferred that dinosaur eggs had an [[amnion]], [[chorion (egg)|chorion]], and an [[allantois]], the three major membranes in modern bird and reptile eggs. Dinosaur eggs vary greatly in size and shape, but even the largest dinosaur eggs (''[[Megaloolithus]]'') are smaller than the largest known bird eggs, which were laid by the extinct [[elephant bird]]. Dinosaur eggs range in shape from spherical to highly elongated (some specimens three times longer than they are wide). Some elongated eggs are symmetrical, whereas others have one rounded end and one pointed end (similar to bird eggs). Most elongated eggs were laid by theropods and have an avian-like eggshell, whereas the spherical eggs typically represent non-theropod dinosaurs.<ref name="Making an Egg">{{cite book|last1=Carpenter|first1=Kenneth|title=Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)|date=1999|publisher=Indiana University Press|location=Bloomington, Indiana|isbn=978-0-253-33497-8|pages=[https://archive.org/details/isbn_9780253334978/page/85 85–107]|chapter=Making an Egg|url=https://archive.org/details/isbn_9780253334978/page/85}}</ref>
[[File:Eggshell Structure diagram.jpg|thumb|240px|Diagram of a two-layered eggshell.]] Fossil dinosaur eggshells, like modern bird and reptile eggshells, are made up of [[calcium carbonate]] crystal units. The basic arrangement and structure of these eggshell units (called the ultrastructure) is used to divide fossil eggs into several basic types, including the spherulitic, prismatic, and ornithoid basic types, which contain dinosaurs.<ref name="How to Study">{{cite book|last1=Carpenter|first1=Kenneth|title=Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)|date=1999|publisher=Indiana University Press|location=Bloomington, Indiana|isbn=978-0-253-33497-8|pages=[https://archive.org/details/isbn_9780253334978/page/122 122–144]|chapter=How to Study a Fossil Egg|url=https://archive.org/details/isbn_9780253334978/page/122}}</ref> Dinosaur eggs further [[#Classification|classified]] by the microstructural aspects of the crystalline structure of the eggshell units and by the type of their pores and their shell ornamentation.<ref name="UCMP"/>
===Layers===
Dinosaur eggshells are divided into one, two, or three layers of distinct ultrastructure.<ref name="UCMP"/><ref>{{Cite journal|last=Dauphin|first=Y.|date=1990|title=Comparative microstructural studies of eggshells. 1. Dinosaurs of the Southern France|journal=Revue de Paléobiologie|volume=9|pages=127–133}}</ref><ref>{{Cite journal|last=Dauphin|first=Y.|date=1990|title=Incidence de l'état diagénétique des coquilles d'oeufs de dinosaures sur la reconnaissance des morphotypes - exemple du Bassin d'Aix en Provence|journal=C. R. Acad. Sci. Paris|volume=sér/ II, 310|pages=849–954}}</ref><ref>{{Cite journal|last1=Dauphin|first1=Y.|last2=Jaeger|first2=J.J.|date=1991|title=Implications de l'analyse microstructurale et géochimique des œufs de dinosaures de la cairanne (Bassin d'Aix en Provence, France, Rognacien inférieur)|journal=Paläontologische Zeitschrift|volume=65|issue=3–4|pages=391–404|doi=10.1007/bf02989853|s2cid=129041143|issn=0031-0220}}</ref>
The innermost layer, known as the mammillary layer or the cone layer, is only found in theropod eggs (the prismatic and ornithoid basic types). It is composed of cone-shaped structures called mammillae at the base of each shell unit. Mammillae are the first part of the eggshell to form. Each mammilla forms from crystals radiating outward from an organic core until they touch neighboring mammillae and grow upwards into the next layer.<ref name="Making an Egg"/><ref name="UCMP">Laura E. Wilson, Karen Chin, Frankie D. Jackson, and Emily S. Bray. [http://www.ucmp.berkeley.edu/science/eggshell/eggshell2.php II. Eggshell morphology and structure]. ''UCMP Online Exhibits: Fossil Eggshell''</ref> In spherulitic eggs, the eggs of non-theropod dinosaurs, the eggshell units grow upward from their organic cores; the base of each eggshell unit is rounded, but is not a true mammilla because it does not have a distinct ultrastructure from the top of the unit.<ref name="Making an Egg"/><ref name="How to Study"/>
The second layer is alternately called the prismatic layer, the columnar layer, the continuous layer, the crystalline layer,<ref name="Making an Egg"/> the cryptoprismatic layer,<ref name="Simon 2014">Simon, D. J. (2014). "[http://scholarworks.montana.edu/xmlui/bitstream/handle/1/8693/SimonD0814.pdf?sequence=1 Giant Dinosaur (theropod) Eggs of the Oogenus Macroelongatoolithus (Elongatoolithidae) from Southeastern Idaho: Taxonomic, Paleobiogeographic, and Reproductive Implications.]" (Doctoral dissertation, Montana State University, Bozeman).</ref> the palisade layer,<ref name="UCMP"/> the spongy layer,<ref name=M1996>{{cite journal |last=Mikhailov |first=Konstantin |date=1996 |title=Bird Eggs in the Upper Cretaceous of Mongolia |journal=Paleontological Journal |volume=30 |issue=1 |pages=114–116}}</ref> or the single layer.<ref name="Vianey-Liaud and Lopez-Martinez 1997">{{cite journal | last1 = Vianey-Liaud | first1 = Monique | last2 = Lopez-Martinez | first2 = Nieves | year = 1997 | title = Late Cretaceous Dinosaur Eggshells from the Tremp Basin, Southern Pyrenees, Lleida, Spain | journal = Journal of Paleontology | volume = 71 | issue = 6| pages = 1157–1171 | doi=10.1017/s002233600003609x| s2cid = 131405598 | url = https://eprints.ucm.es/id/eprint/69803/1/3Vianey%26LopezM97-1.pdf }}</ref> In this layer, the shell units can be distinct, partially fused together, or entirely continuous.<ref name="How to Study"/> In some dinosaur eggs, the prismatic layer exhibits squamatic ultrastructure, where the prismatic structure is obscured by a rough texture resembling lizard skin.<ref name="UCMP"/><ref name="How to Study"/>
Though rare in non-avian dinosaurs, some theropod eggs and most bird eggs have a third layer (known as the external layer) made up of vertical calcite crystals.<ref name="UCMP"/><ref name="Making an Egg"/>
===Pore canals===
In all eggs, the embryo must breathe. In egg-laying amniotes (including dinosaurs), pore canals cutting through the eggshell allow gas exchange between the embryo and the outside world. Dinosaur eggshells exhibit a lot of diversity in pore size, density, and shape. One early attempt at classification of dinosaurian eggs, proposed by the Soviet paleontologist A. Sochava, was based on grouping eggs by their pore systems.<ref name="Intro">{{cite book|last1=Carpenter|first1=Kenneth|last2=Hirsch|first2=Karl|last3=Horner|first3=John|editor1-last=Carpenter|editor1-first=Kenneth|editor2-last=Hirsch|editor2-first=Karl|editor3-last=Horner|editor3-first=John|title=Dinosaur Eggs and Babies|date=1994|publisher=University of Cambridge|location=Trumpington Street, Cambridge|isbn=978-0-521-44342-5|pages=1–11|chapter=Introduction}}</ref> This system was abandoned when it was discovered that different eggs could have very similar pores, but pore systems do play an important role in modern eggshell parataxonomy.<ref name="How to Study"/> The density and width of the pores, combined with the eggshell's thickness can be used to predict the [[gas conductance]] of a dinosaur's egg.<ref name="UCMP"/> This can provide both information about nesting behavior and about the climate: eggs buried in sediment have higher rates of gas conductance than those laid in the open, and eggs laid in arid environments have lower gas conductance (to prevent water loss) than those laid in more humid conditions.<ref name="UCMPV">Laura E. Wilson, Karen Chin, Frankie D. Jackson, and Emily S. Bray. [http://www.ucmp.berkeley.edu/science/eggshell/eggshell2.php V. Paleobiology and eggs]. ''UCMP Online Exhibits: Fossil Eggshell''</ref>
Paleontologist and fossil egg expert Kenneth Carpenter catalogued six types of pore systems:<ref name="How to Study"/>
#Angusticanaliculate - Long, narrow, straight pores with low pore density. These eggs would have a low gas exchange rate, and therefore they were typically laid in dry areas.<ref name="How to Study"/>
#Tubocanaliculate - Large diameter pores with funnel-shaped openings on both inner and outer surfaces of the shell. These eggs would have a high gas exchange rate, and therefore were probably buried in humid mounds.<ref name="How to Study"/>
#Multicanaliculate - Numerous large, branching, and closely spaced pore canals. They have a high gas exchange rate, so like tubocanaliculate eggs they were probably also buried humid mounds.<ref name="How to Study"/>
#Prolatocanaliculate - Pores vary in width throughout their length. Gas exchange water loss rates are variable, so these eggs could have been laid in many different environments. This type is subdivided into foveocanaliculate with larger pore openings, and lagenocanaliculate with narrower pore openings.<ref name="How to Study"/>
#Rimocanaliculate - Very narrow slitlike pore canals. This pore system is seen in modern ostriches, so these eggs were laid in open nests, similar to how ostriches do today.<ref name="How to Study"/>
#Obliquicanaliculate - These canals cut diagonally through multiple eggshell units instead of going between them like in other pore systems. Obliquicanaliculate pores are only found in a single oogenus: ''[[Preprismatoolithus]]''.<ref name="How to Study"/>
===Ornamentation===
Unlike most modern eggs, many dinosaur eggs had a rough texture formed by nodes and ridges ornamenting the surface of their shell.<ref name="UCMP"/> This is predominant in Cretaceous dinosaur eggs, but very rare in eggs from the Jurassic or Triassic.<ref name="Nests">{{cite book|last1=Moratalla|first1=J.J.|last2=Powell|first2=J.E.|editor1-last=Carpenter|editor1-first=Kenneth|editor2-last=Hirsch|editor2-first=Karl|editor3-last=Horner|editor3-first=John|title=Dinosaur Eggs and Babies|date=1994|publisher=Cambridge University Press|location=The Pitt Building, Trumpington Street, Cambridge|pages=37–46|chapter=Dinosaur Nesting Patterns}}</ref> Because of the lack of modern analogues, the purpose of eggshell ornamentation is unknown,<ref name="UCMP"/> but many functions have been proposed.<ref name="Nests"/> Possibly, they provided extra strength to the eggshell without having pore canals too long for adequate gas exchange. They could also have helped keep substrate away from the pore openings of eggs that were buried, but modern [[turtle]]s and [[crocodylian]]s which bury their eggs have smooth eggshells, so this adaptation is not necessary for animals which bury their eggs. Another hypothesis, proposed by R. M. Mellon in [[1982 in paleontology|1982]] in his [[senior thesis]] at [[Princeton University]], is that the ridges and nodes would have formed pathways for gas to flow across the surface of the eggshell, preventing accumulation of too much [[Carbon dioxide|CO<sub>2</sub>]] and aiding the flow of oxygen and water vapor.<ref name="Nests"/>
Since it varies from egg to egg, the texture of an eggshell's ornamentation is useful for classification. Six types of ornamentation were catalogued by Carpenter in 1999:<ref name="How to Study"/>
#Compactituberculate - The dome-shaped tops of the shell units form a dense covering of nodes on the surface of the eggshell. This type of ornamentation is most commonly seen in [[Megaloolithidae|megaloolithids]].<ref name="Soto">{{cite journal | last1 = Soto | first1 = M. | last2 = Perea | first2 = D. | last3 = Cambiaso | first3 = A.V. | year = 2012 | title = First sauropod (Dinosauria: Saurischia) remains from the Guichón Formation, Late Cretaceous of Uruguay | url = https://www.researchgate.net/publication/232399931 | journal = Journal of South American Earth Sciences | volume = 33 | issue = 1| pages = 68–79 | doi = 10.1016/j.jsames.2011.08.003 | bibcode = 2012JSAES..33...68S }}</ref>
#Sagenotuberculate - The nodes and ridges form a netlike pattern interspersed with pits and grooves.
#Dispersituberculate - Scattered nodes. This ornamentation is seen on the poles of elongated eggs, which may have allowed accumulations CO<sub>2</sub> at the poles to escape between the nodes.<ref name="Nests"/>
#Lineartuberculate - Ridges, and chains of ridges and nodes form lines parallel to the long axis of the egg.
#Ramotuberculate - Irregular chains of nodes, typically found as a transition between the lineartuberculate midsection and dispersituberculate ends of elongated eggs.
#Anastomotuberculate - Ridges similar to lineartuberculate, but instead form wavy, branching, or [[anastomosing]] patterns resembling the water ripple marks in sand.
==Classification==
The classification of dinosaur eggs is based on the structure of the egg shells viewed in thin section via microscope, although new techniques such as electron backscatter diffraction have been used.<ref>{{cite journal|journal=[[PLOS ONE]]|volume=11|issue=5|last1=Moreno-Azanza|first1=Miguel|last2=Bauluz|first2=Blanca|last3=Canudo|first3=José Ignacio|last4=Gasca|first4=José Manuel|last5=Fernández-Baldor|first5=Fidel Torcida|title=Combined Use of Electron and Light Microscopy Techniques Reveals False Secondary Shell Units in Megaloolithidae Eggshells|publication-date=May 4, 2016|doi=10.1371/journal.pone.0153026|pmid=27144767|year=2016|page=e0153026|bibcode=2016PLoSO..1153026M|pmc=4856302|doi-access=free}}</ref> There are three main categories of dinosaur eggs: spherulitic (sauropods and [[Hadrosaurid|hadrosaurs]]),<ref name="basic-spherulitic-136-137" /> [[Prism (geometry)|prismatic]],<ref name="basic-prismatic-137" /> and ornithoid ([[Theropoda|theropods]], including modern birds).<ref name=ubristol/>
===Oogenera===
[[Oogenus|Oogenera]] are taxonomic names for types of eggshell. Nearly three dozen oogenera have been named for dinosaur eggs:
[[File:Segnosaurus nest 2.jpg|thumb|[[Therizinosaur]] nest and eggs (''[[cf.]]'' ''[[Segnosaurus]]'') in from ''[[Dinosaurland]]'' in [[Lyme Regis]], England.]]
{{div col|colwidth=20em}}
* ''[[Ageroolithus]]''
* ''[[Apheloolithus]]''<ref name=DFG03 />
* ''[[Boletuoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=82906 The Palaeobiology Database]</ref>
* ''[[Cairanoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67205 The Palaeobiology Database]</ref>
* ''[[Continuoolithus]]''<ref name=DFG03/>
* ''[[Dendroolithus]]''<ref name=DFG03/>
* ''[[Dictyoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67198 The Palaeobiology Database]</ref>
* ''[[Dispersituberoolithus]]''
* ''[[Ellipsoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=81056 The Palaeobiology Database]</ref>
* ''[[Elongatoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67185 The Palaeobiology Database]</ref>
* ''[[Faveoolithus]]''<ref name=DFG03 />
* ''[[Heishanoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=81709 The Palaeobiology Database]</ref>
* ''[[Laevisoolithus]]''
* ''[[Macroolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67183 The Palaeobiology Database]</ref>
* ''[[Macroelongatoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=98798 The Palaeobiology Database]</ref>
* ''[[Megaloolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=65584 The Palaeobiology Database]</ref>
* ''[[Nanshiungoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67189 The Palaeobiology Database]</ref>
* ''[[Oblongoolithus]]''
* ''[[Ovaloolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=56741 The Palaeobiology Database]</ref>
* ''[[Pachycorioolithus]]''<ref name="Lawver et al 2016">{{cite journal|last1=Lawver|first1=Daniel R.|last2=Jin|first2=Xingsheng|last3=Jackson|first3=Frankie D.|last4=Wang|first4=Qiongying|title=An Avian Egg from the Lower Cretaceous (Albian) Liangtoutang Formation of Zhejiang Province, China|journal=Journal of Vertebrate Paleontology|date=2016|volume=36|issue=3|page=e1100631|doi=10.1080/02724634.2016.1100631|s2cid=88169746}}</ref>
* ''[[Paraspheroolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67196 The Palaeobiology Database]</ref>
* ''[[Phaceloolithus]]''<ref name=DFG03/>
* ''[[Placoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=68519 The Palaeobiology Database]</ref>
* ''[[Porituberoolithus]]''
* ''[[Polyclonoolithus]]''<ref name="Xie et al 2016">{{cite journal | last1 = Xie | first1 = J.-F. | last2 = Zhang | first2 = S.-K. | last3 = Jin | first3 = X.-S. | last4 = Li | first4 = D.-Q. | last5 = Zhou | first5 = L.-Q. | year = 2016 | title = A new type of dinosaur eggs from Early Cretaceous of Gansu Province, China | url = http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201512/P020151203499501638411.pdf | journal = Vertebrata PalAsiatica | volume = 54 | issue = 1 | pages = 1–10 | access-date = January 11, 2016 | archive-url = https://web.archive.org/web/20160129003559/http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201512/P020151203499501638411.pdf | archive-date = January 29, 2016 | url-status = dead }}</ref>
* ''[[Preprismatoolithus]]''<ref name=DFG03/>
* ''[[Prismatoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=65562 The Palaeobiology Database]</ref>
* ''[[Protoceratopsidovum]]''<ref name="The Palaeobiology Database">[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=84312 The Palaeobiology Database]</ref>
* ''[[Pseudogeckoolithus]]''
* ''[[Shixingoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67195 The Palaeobiology Database]</ref>
* ''[[Sphaerovum]]''<ref name=DFG03/>
* ''[[Spheroolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67290 The Palaeobiology Database]</ref>
* ''[[Spheruprismatoolithus]]''<ref name="The Palaeobiology Database"/>
* ''[[Stromatoolithus]]''<ref name=DFG03/>
* ''[[Subtiliolithus]]''<ref name=DFG03/>
* ''[[Tacuarembovum]]''<ref name=DFG03/>
* ''[[Trachoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=81708 The Palaeobiology Database]</ref>
* ''[[Tristraguloolithus]]''
* ''[[Youngoolithus]]''<ref name=DFG03/>
{{div col end}}
===Embryos===
Dinosaur embryos, the animal inside the eggs, are very rare but useful to understand [[ontogeny]], [[heterochrony]], and dinosaur [[systematics]].
Embryo fossils are known from:
{{div col|colwidth=20em}}
* ''[[Beibeilong]]''
* ''[[Citipati (dinosaur)|Citipati]]''<ref>{{cite journal | last1 = Norell | first1 = M. A. | last2 = Clark | first2 = J. M. | last3 = Dashzeveg | first3 = D. | last4 = Barsbold | first4 = T. | last5 = Chiappe | first5 = L. M. | last6 = Davidson | first6 = A. R. | last7 = McKenna | first7 = M. C. | last8 = Novacek | first8 = M. J. | year = 1994 | title = A theropod dinosaur embryo, and the affinities of the Flaming Cliffs Dinosaur eggs | journal = Science | volume = 266 | issue = 5186| pages = 779–782 | doi=10.1126/science.266.5186.779| pmid = 17730398 | bibcode = 1994Sci...266..779N | s2cid = 22333224 }}</ref>
* ''[[Heyuannia]]''
* ''[[Lufengosaurus]]''
* ''[[Lourinhanosaurus]]''<ref name="mateus-et-al" /><ref name="dericqles-et-al" />
* ''[[Massospondylus]]''<ref name="reisz-et-al" />
* ''[[Maiasaura]]''
* ''[[Troodon]]''<ref name="horner-weishampel" />
{{div col end}}
==Taphonomy==
{{Main|Egg taphonomy}}
The formation of fossil eggs begins with the original egg itself. Not all eggs that end up fossilizing experience the death of their embryo beforehand. Fossil eggs with open tops are common and could result from the preservation of eggs that hatched successfully.<ref name="enbd-fossilize-112" /> Dinosaur eggs whose embryos died were likely victims of similar causes to those that kill embryos in modern reptile and bird eggs. Typical causes of death include congenital problems, diseases, [[suffocation]] from being buried too deep, inimical temperatures, or too much or too little water.<ref name="enbd-fossilize-113" />
Whether or not hatching was successful, burial would begin with sediments gradually entering any large openings in the shell.<ref name="enbd-fossilize-112" /> Even intact eggs are likely to fill with sediment once they crack under the strain of deep burial. Sometimes, though, fossilization can begin fast enough to prevent the eggs from being cracked. If the water table is high enough dissolved minerals like calcite can percolate through the pores of the eggshell. When the egg is completely filled it can become sturdy enough to withstand the weight of the overlying sediments.<ref name="enbd-fossilize-113" /> Not all fossil egg specimens are of complete specimens, however. Individual pieces of eggshell are much more robust than the entire egg and can be transported intact long distances from where they were originally laid.<ref name="enbd-fossilize-108" />
When the egg is buried deeply enough, the bacteria decomposing it no longer have access to oxygen and need to power their metabolisms with different substances. These physiological changes in the decomposers also alter the local environment in a way that allows certain minerals to be deposited, while others remain in solution.<ref name="enbd-fossilize-113" /> Generally, however, a fossilizing egg's shell keeps the same calcite it had in life, which allows scientists to study its original structure millions of years after the developing dinosaur hatched or died.<ref name="enbd-fossilize-114" /> However, eggs can also sometimes be altered after burial. This process is called [[diagenesis]].<ref name="enbd-fossilize-114" /> One form of diagenesis is a microscopic [[Hatching#Variations|cross-hatched]] pattern imposed on the eggshell by the pressure of being buried deeply.<ref name="enbd-fossilize-114-115" /> If the pressure gets severe enough, sometimes the eggshell's internal microscopic structure can be completely destroyed. Diagenesis can also happen chemically in addition to physically. The chemical conditions of a decomposing egg can make it easy for silica to be incorporated into eggshell and damage its structure. When iron-bearing substances alter eggshell it can be obvious because compounds like [[hematite]], [[pyrite]], and [[iron sulfide]] can turn the shell blackish or rusty colors.<ref name="enbd-fossilize-115" />
===Depositional environments===
Dinosaur eggs are known from a variety of depositional environments.
'''[[Beach sands]]:''' Beach sands were a good place for dinosaurs to lay their eggs because the sand would be effective at absorbing and holding enough heat to incubate the eggs. One ancient beach deposit in northeastern Spain actually preserves about 300,000 fossil dinosaur eggs.<ref name="enbd-fossilize-111" />
'''[[Floodplains]]:''' Dinosaurs often laid their eggs on ancient floodplains. The [[mudstone]]s deposited at these sites are therefore excellent sources of dinosaur egg fossils.<ref name="enbd-fossilize-108" />
'''[[Sand dunes]]:''' Many dinosaur eggs have been recovered from sandstone deposits that formed in the ancient dune fields of what are now northern China and Mongolia.<ref name="enbd-fossilize-110" /> The presence of ''[[Oviraptor]]'' preserved in their life brooding position suggests that the eggs, nests, and parents may have been rapidly buried by sandstorms.<ref name="enbd-fossilize-111" />
==Excavation and preparation==
Usually the first evidence of fossil dinosaur eggs to be discovered are shell fragments that have eroded away from the original eggs and been transported downhill by the elements.<ref name="enbd-collecting-115" /> If the source eggs can be found the area must be examined for more unexposed eggs. If the paleontologists are fortunate enough to have found a nest, the number and arrangement of the eggs must be estimated. Excavation must proceed to significant depth since many dinosaur nests include multiple layers of eggs. As the underside of the nest is excavated, it would be covered by material like newspaper, tin foil, or tissue. Afterwards, the entire block is covered in multiple layers of plaster-soaked strips of burlap. When the plaster is dried, the block is undercut the rest of the way and turned over.<ref name="enbd-collecting-117" />
The fine work of cleaning the egg fossils is performed in a laboratory. Preparation usually begins from the underside of the block, which tends to be the best preserved.<ref name="enbd-collecting-117" /> Because of their fragility, cleaning fossil eggs requires patience and skill.<ref name="enbd-collecting-117-118" /> Scientists use delicate instruments like dental picks, needles, small [[pneumatic]] engraving tools, and [[X-Acto]] knives.<ref name="enbd-collecting-117" /> Scientists must determine at what point to stop cleaning based on their own criteria. If eggs are fully extracted they can be more fully studied individually at the cost of information regarding the spatial relationships between eggs or if the eggs had hatched. Commercial fossil dealers tend to expose only the bottom of the eggs since the topsides might be damaged by hatching and therefore less visually appealing to potential customers.<ref name="enbd-collecting-118" />
==Research techniques==
===Acid dissolution===
Acids can be used to learn more about fossil eggs. Diluted [[acetic acid]] or [[EDTA]] can be used to expose the microstructure of shell that has been damaged by weathering. Acids are also used to extract embryo skeletons from the egg encasing them.<ref name="enbd-tools-128" /> Even fossilized soft tissue like muscle and cartilage as well as fat globules from the original [[egg yolk]] can be uncovered using this method.<ref name="enbd-tools-130" /> Amateur paleontologist [[Terry Manning]] has been credited with groundbreaking work developing this technique.<ref>https://embryo.asu.edu/pages/acid-dissolution-fossil-dinosaur-eggs Last paragraph</ref> First, the paleontologist must submerge the egg in a very dilute phosphoric acid bath. Since the acid solution can penetrate the egg, every few days the specimen must be soaked in distilled water to prevent the acid from damaging the embryo before it is even exposed. If embryonic fossil bone is revealed after drying from the water bath, the exposed fossils must be delicately cleaned with fine instruments like needles and paint brushes. The exposed bone is then coated with plastic preservatives like [[Acryloid B67]], [[Paraloid B72]], or [[Vinac B15]] to protect it from the acid when submerged for another round. The complete process can take months before the whole embryo is revealed.<ref name="enbd-tools-128" /> Even then only about 20% of the eggs subjected to the process reveal any embryo fossils at all.<ref name="enbd-tools-128-130" />
===CAT scans===
[[CAT scans]] can be used to infer the 3D structure of a fossil egg's interior by compiling images taken of slices through the egg in small regular increments. Scientists have tried to use CAT scans to look for embryo fossils contained inside the egg without having to damage the egg itself by physically extracting them. However, as of Ken Carpenter's 1999 book on dinosaur eggs, ''Eggs, Nests, and Baby Dinosaurs'', all alleged embryos discovered using this method were actually false alarms. Variations in the type of infilling mineral or cement binding the infilling sediment into rock sometimes resemble bones in CAT scan images. Sometimes eggshell fragments that fell back into the egg when it hatched have been mistaken for embryonic bones.<ref name="enbd-tools-128" /><ref name="enbd-collecting-7-11" /> The use of CAT scans to search for embryonic remains is actually conceptually flawed since embryonic bones have not yet [[Ossification|mineralized]]. Since the infilling sediment is their only source of minerals they will be preserved at basically the same density and therefore have poor visibility in the scan. The validity of this issue has been confirmed by performing Cat scans on fossil eggs known to have embryos inside and noting their poor visibility in the scan images. The only truly reliable way to discover a dinosaur embryo is to cut the egg open or dissolve some of its eggshell away.<ref name="enbd-tools-128" />
===Cathodoluminescence===
[[Cathodoluminescence]] is the most important tool paleontologists have for revealing whether or not the [[calcium]] in fossil eggshell has been altered.<ref name="enbd-tools-133" /> Calcite in eggshell is either pure or rich in [[calcium carbonate]]. However, the calcite composing the egg can be altered after burial to include significant calcium content. Cathodoluminescence causes calcite altered in this fashion to glow orange.<ref name="enbd-tools-134" />
===Gel electrophoresis===
[[Gel electrophoresis]] has been used in attempts to identify the [[amino acids]] present in the organic components of dinosaur eggshell. Contact with human skin can contaminate eggs with foreign amino acids, so only untouched eggs can be investigated using this technique. [[EDTA]] can be used to dissolve the calcite of the eggshell while leaving the shell's organic content intact. The resultant organic residue would be blended and then implanted into [[gel]]. Electricity would then be run through the sample, causing the amino acids to migrate through the gel until they stop at levels determined by their physical properties. [[Protein silver stain]] is then used to dye the amino acids and make them visible.<ref name="enbd-tools-133" /> The bands of amino acids from the dinosaur eggs can then be compared with the banding of samples with known composition for identification.<ref name="enbd-tools-133" />
Gel electrophoresis is not necessarily a perfect means of discovering the amino acid composition of dinosaur eggshell because sometimes the amount or type of amino acids present could be altered during or after preservation. One potential confounding factor would be the heating of deeply buried egg fossils, which can break down amino acids. Another potential source of error is groundwater, which can leach away amino acids. These issues cast doubt as to whether the results these sorts of studies give are reliable as the actual composition of the eggshell's organic material in life. However, studies applying these techniques have made suggestive findings, including amino acid profiles in dinosaur eggs similar to those in modern birds.<ref name="enbd-tools-133" />
===Geneva lens measure===
The [[Geneva Lens Measure]] is a device used to measure curved surfaces. It is most commonly used by [[opticians]] to measure lenses but can also be used by paleontologists to estimate the life size of dinosaur eggs from shell fragments. The instrument can be used to help estimate the size of fossil eggshells by measuring their curved surfaces. Since most eggs aren't perfectly round measurements from multiple parts of the egg with varying shell curvatures may be needed to get a full idea of the egg's size. Ideally an eggshell fragment being used to estimate the full size of an egg should be more than 3 cm long. Smaller eggshell fragments are better suited to other methods of study, like the [[Obrig radius dial gauge]]. The Geneva Lens measure gives units in [[diopters]] which must be converted to the radius in millimeters. Use of the Geneva Lens Measure to estimate the size of a fossil egg was first done by [[Sauer]] on fossil ostrich eggs.<ref name="enbd-tools-134" />
===Light microscopy===
[[Light microscopy]] can be used to magnify the structure of dinosaur eggshell for scientific research. To do so an eggshell fragment must be embedded in [[epoxy]] [[resin]] and sliced into a thin section with a thin-bladed [[rock saw]]. This basic method was invented by French paleontologist [[Paul Gervais]] and has remained almost unchanged ever since. Horizontally cut thin sections are called tangential thin sections while vertically cut thin sections are called radial sections. Regardless of direction, the sample must be abraded by fine-grit [[Sand paper|sand]] or [[emery paper]] until it is [[translucent]]. Then the structure of the shell's [[calcite|calcite crystals]] or pores can be examined under a [[petrographic microscope]].<ref name="enbd-tools-122" /> The calcite crystal structure of dinosaur eggshell can be classified by their effect on [[polarized light]]. Calcite is capable of acting as a polarizing light filter.<ref name="enbd-tools-124" /> When a microscopic thin section sample is rotated relative to polarized light it can eventually block all the light and seem opaque. This phenomenon is called extinction. Different varieties of dinosaur eggs with their different calcite crystal structures have different light extinction properties that can be used to identify and distinguish even eggs that seem very similar on the surface.<ref name="enbd-tools-125" /> To reconstruct the three-dimensional structures of the shell's pore channels scientists require a series of multiple radial sections.<ref name="enbd-tools-122" />
===Scanning electron microscopy===
[[Scanning electron microscopy]] is used to view dinosaur eggshell under even greater magnification than is possible with light microscopy. However, this does not mean that scanning electron microscopy is necessarily the superior research method. Since both techniques provide differing amounts and types of information they can be used together synergistically to provide a more complete understanding of the specimen under scrutiny. Eggshell specimens best suited for scanning electron microscopy are those recently broken because such a break will usually occur along the plane of the eggshell's calcite crystal lattice. First, a small specimen would be covered with a very thin layer of [[gold]] or [[platinum]]. The specimen would then be bombarded with [[electrons]]. The electrons bounce back off the metal and due to their small size, can be used to form a detailed image of the specimen.<ref name="enbd-tools-125" />
===Mass spectrometry===
[[Mass spectrometry]] is a method for determining eggshell composition that uses a device called a mass spectrometer. First, the eggshell sample must be powdered and placed in the mass spectrometer's vacuum chamber.<ref name="enbd-tools-130" /> The powder is vaporized by the heat of an intense laser beam. A stream of electrons then bombard the gaseous eggshell molecules, which breaks down the molecules in the eggshell and imbues them with a positive charge. A magnetic field then sorts them by mass before they are detected by the spectrometer.<ref name="enbd-tools-131" /> One application of mass spectrometry has been to study the isotope ratios of dinosaur eggshell in order to ascertain their diets and living conditions. However this research is complicated by the fact that isotope ratios can be altered post mortem before or during fossilization. Bacterial decomposition can alter [[carbon isotope]] ratios in eggs and [[groundwater]] can alter the [[oxygen isotope]] ratios of eggshell.<ref name="enbd-tools-132" />
===X rays===
X-ray equipment, like CAT scans, are used to study the interior of fossil eggs. Unlike CAT scans, x-ray imaging condenses the entire interior of the egg into a single two-dimensional image rather than a series of images documenting the interior in three dimensions. X-ray imaging in the context of dinosaur research has generally been used to look for evidence of embryonic fossils contained inside the egg. However, as of Kenneth Carpenter's 1999 book ''Eggs, Nests, and Baby Dinosaurs'', all putative embryos discovered using x-rays have been misidentifications. This is because the use of x-rays to find embryos is conceptually flawed. Embryo bones are incompletely developed and will generally lack their own mineral content, as such the only source of minerals for these bones is the sediment that fills the egg after burial. The fossilized bones will therefore have the same density as the sediment filling the interior of the egg which served as the source for their mineral content and will be poorly visible in an x-ray image. So far the only reliable method for examining embryonic fossils preserved in dinosaur eggs is to physically extract them through means such as acid dissolution.<ref name="enbd-tools-128" />
X-rays can be used to chemically analyze dinosaur eggshell. This technique requires pure shell samples, so the fossil must be completely free of its surrounding rock matrix. The shell must then be further cleaned by an [[ultrasonic cleaning|ultrasonic bath]]. The sample can then be bombarded by electrons emitted by the same sort of probe used by scanning electron microscopes. Upon impact with the samples x-rays are emitted that can be used to identify the composition of the shell.<ref name="enbd-tools-130" />
[[X-ray diffraction]] is a method for determining eggshell composition that uses X-rays to directly bombard powdered eggshell. Upon impact some of the x-rays will be diffracted at different angles and intensities depending on the specific elements present in the eggshell.<ref name="enbd-tools-130" />
'''Allosterics'''
In order to test out how allosterics played a part in dinosaur egg size, scientists used modern day animal species such as birds, crocodiles, and tortoises in their experiment. They set the bird group as representing the theropods with the reptiles representing the sauropod group. The laid eggs of each species where compared with one another over the course of the study as well as against the fossilized eggs. The results that was retrieved from the experiment was that while sauropods laid smaller eggs in greater amounts each year, dinosaur of the theropod group was revealed to lay larger eggs less frequently over the years, similar to modern birds today.
==Footnotes==
{{Reflist|3|refs=
<ref name=ubristol>{{Citation
| title = What are dinosaur eggs?
| url = http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html
| archive-url = https://web.archive.org/web/20140201213751/http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html
| archive-date = February 1, 2014
| url-status = dead
}}</ref>
<ref name="mateus-et-al">Mateus et al. (1998).</ref>
<ref name="dericqles-et-al">de Ricqles et al. (2001).</ref>
<ref name="DFG03">Glut (2003).</ref>
<ref name="enbd-tools-122">"Tools of the Trade," Carpenter (1999); page 122.</ref>
<ref name="enbd-tools-124">"Tools of the Trade," Carpenter (1999); page 124.</ref>
<ref name="enbd-tools-125">"Tools of the Trade," Carpenter (1999); page 125.</ref>
<ref name="enbd-tools-128">"Tools of the Trade," Carpenter (1999); page 128.</ref>
<ref name="enbd-tools-128-130">"Tools of the Trade," Carpenter (1999); pages 128–130.</ref>
<ref name="enbd-tools-130">"Tools of the Trade," Carpenter (1999); page 130.</ref>
<ref name="enbd-tools-131">"Tools of the Trade," Carpenter (1999); page 131.</ref>
<ref name="enbd-tools-132">"Tools of the Trade," Carpenter (1999); page 132.</ref>
<ref name="enbd-tools-133">"Tools of the Trade," Carpenter (1999); page 133.</ref>
<ref name="enbd-tools-134">"Tools of the Trade," Carpenter (1999); page 134.</ref>
<ref name="enbd-collecting-115">"Collecting Eggs," Carpenter (1999); page 115.</ref>
<ref name="enbd-collecting-117">"Collecting Eggs," Carpenter (1999); page 117.</ref>
<ref name="enbd-collecting-117-118">"Collecting Eggs," Carpenter (1999); pages 117–118.</ref>
<ref name="enbd-collecting-118">"Collecting Eggs," Carpenter (1999); page 118.</ref>
<ref name="enbd-collecting-7-11">"Fig 7.11," Carpenter (1999); page 118.</ref>
<ref name="enbd-fake-118">"Fake Eggs," Carpenter (1999); page 118.</ref>
<ref name="enbd-fake-119">"Fake Eggs," Carpenter (1999); page 119.</ref>
<ref name="enbd-fake-119-120">"Fake Eggs," Carpenter (1999); pages 119–120.</ref>
<ref name="enbd-fake-120">"Fake Eggs," Carpenter (1999); page 120.</ref>
<ref name="enbd-fake-120-121">"Fake Eggs," Carpenter (1999); pages 120–121.</ref>
<ref name="enbd-fake-121">"Fake Eggs," Carpenter (1999); page 121.</ref>
<ref name="enbd-fossilize-108">"How to Fossilize an Egg," Carpenter (1999); page 108.</ref>
<ref name="enbd-fossilize-110">"How to Fossilize an Egg," Carpenter (1999); page 110.</ref>
<ref name="enbd-fossilize-111">"How to Fossilize an Egg," Carpenter (1999); page 111.</ref>
<ref name="enbd-fossilize-112">"How to Fossilize an Egg," Carpenter (1999); page 112.</ref>
<ref name="enbd-fossilize-113">"How to Fossilize an Egg," Carpenter (1999); page 113.</ref>
<ref name="enbd-fossilize-114">"How to Fossilize an Egg," Carpenter (1999); page 114.</ref>
<ref name="enbd-fossilize-114-115">"How to Fossilize an Egg," Carpenter (1999); pages 114–115.</ref>
<ref name="enbd-fossilize-115">"How to Fossilize an Egg," Carpenter (1999); page 115.</ref>
<ref name="horner-weishampel">"Correction: A comparative embryological study of two ornithischian dinosaurs," Horner and Weishampel (1996); page 103.</ref>
<ref name="reisz-et-al">"Abstract," Reisz et al. (2005); page 761.</ref>
<ref name="basic-spherulitic-136-137">"Basic Types Eggshell: Spherulitic Basic Type," Carpenter (1999); pages 136-137.</ref>
<ref name="basic-prismatic-137">"Basic Types Eggshell: Prismatic Basic Type," Carpenter (1999); page 137.</ref>
<ref name="enbd-first-1">"First Discoveries," Carpenter (1999); page 1.</ref>
<!-- Not in use
<ref name="enbd-classification-148-149">"Growth of the Modern Classification System," Carpenter (1999); pages 148-149.</ref>
<ref name="enbd-classification-149">"Growth of the Modern Classification System," Carpenter (1999); page 149.</ref>
Not in use-->
}}
==References==
* Carpenter, Kenneth (1999). ''Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)'', Indiana University Press; {{ISBN|0-253-33497-7}}.
* Deeming, D. C. and M. W. J. Ferguson (eds.) 1991. Egg incubation: its effect on embryonic development in birds and reptiles. Cambridge University Press, UK. 448pp.
* {{Citation |last=Glut |first=Donald F. |title=Dinosaurs: The Encyclopedia. 3rd Supplement |year=2003 |publisher=McFarland & Company, Inc. |location=Jefferson, North Carolina |isbn=978-0-7864-1166-5 |chapter=Appendix: Dinosaur Tracks and Eggs |pages=[https://archive.org/details/dinosaursencyclo00glut_2/page/613 613–652] |chapter-url=https://archive.org/details/dinosaursencyclo00glut_2/page/613 }}
* {{cite journal | last1 = Horner | first1 = John R. | last2 = Weishampel | first2 = David B. | year = 1996 | title = A comparative embryological study of two ornithischian dinosaurs - a correction | journal = Nature | volume = 383 | issue = 6595| pages = 256–257 | doi = 10.1038/383103b0 | doi-access = free | bibcode = 1996Natur.383..103H }}
* {{cite journal | last1 = Mateus | first1 = I | last2 = Mateus | first2 = H | last3 = Antunes | first3 = MT | last4 = Mateus | first4 = O | last5 = Taquet | first5 = P | last6 = Ribeiro | first6 = V | last7 = Manuppella | first7 = G | year = 1998 | title = Upper Jurassic theropod dinosaur embryos from Lourinhã (Portugal) | journal = Memórias da Academia das Ciências de Lisboa | volume = 37 | pages = 101–110 }}
* Moskvitch, Katia. [https://www.bbc.co.uk/news/science-environment-11734616 "Eggs with the Oldest Known Embryos of a Dinosaur Found"]. BBC News. November 12, 2010.
* {{cite journal | last1 = de Ricqlès | first1 = A. | last2 = Mateus | first2 = O. | last3 = Antunes | first3 = M. T. | last4 = Taquet | first4 = P. | year = 2001 | title = Histomorphogenesis of embryos of Upper Jurassic theropods from Lourinhã (Portugal) | journal = Comptes Rendus de l'Académie des Sciences, Série IIA | volume = 332 | issue = 10| pages = 647–656 | doi=10.1016/s1251-8050(01)01580-4| bibcode = 2001CRASE.332..647D }}
* {{cite journal | last1 = Reisz | first1 = Robert R. | last2 = Scott | first2 = Diane | last3 = Sues | first3 = Hans-Dieter | last4 = Evans | first4 = David C. | last5 = Raath | first5 = Michael A. | year = 2005 | title = Embryos of an Early Jurassic prosauropod dinosaur and their evolutionary significance | journal = Science | volume = 309 | issue = 5735| pages = 761–764 |bibcode = 2005Sci...309..761R | doi=10.1126/science.1114942 | pmid = 16051793| s2cid = 37548361 | url = http://doc.rero.ch/record/14975/files/PAL_E2124.pdf }}
* Skinner, Justin.[http://www.insidetoronto.com/news/local/article/812684--rom-puts-oldest-dinosaur-eggs-ever-discovered-on-display "ROM Puts Oldest Dinosaur Eggs Ever Discovered on Display"]. insidetoronto.com. May 6, 2010.
* {{Citation
| work = University of Bristol Earth Sciences
| title = What are dinosaur eggs?
| url = http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html
| access-date = June 20, 2013
| archive-url = https://web.archive.org/web/20140201213751/http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html
| archive-date = February 1, 2014
| url-status = dead
}}
==External links==
{{Portal|Dinosaurs}}
* {{Commons category-inline|Dinosauria eggs}}
{{Eggs}}
{{Authority control}}
[[Category:Eggs]]
[[Category:Dinosaur trace fossils]]
[[Category:Dinosaur reproduction]]' |
New page wikitext, after the edit (new_wikitext) | '{{Short description|Vessel for dinosaur embryo development}}
{{Use mdy dates|date=July 2013}}
[[File:Indroda eggs.JPG|thumb|160px|Fossilized [[sauropod]] eggs displayed at [[Indroda Dinosaur and Fossil Park]]]]
bbc.co.uk/news/science-environment-11734616 "Eggs with the Oldest Known Embryos of a Dinosaur Found"]. BBC News. November 12, 2010.</ref>
==History==
{{Main|Timeline of egg fossil research}}
[[File:Citipati embryo.jpg|thumb|A ''[[Citipati (dinosaur)|Citipati]] osmolskae'' egg with preserved embryo, at the [[American Museum of Natural History|AMNH]].]]sngfjkfrjgfrffgfhrlibgfkdjrgtiufkjdgijfkrgtijbutibuer (1999); page 4.</ref> These eggs were mistakenly attributed to the locally abundant herbivore ''[[Protoceratops]]'', but are now known to be ''[[Oviraptor]]'' eggs. Egg discoveries continued to mount all over the world, leading to the development of multiple competing classification schemes.
==Identification==
Fossil dinosaur eggshell fragments can be recognized based on three important traits. Their thickness should be roughly uniform, they are usually slightly curved, and their surface is covered in tiny pores. Less frequently, the [[wikt:concave|concave]] underside of the eggshell fragment will preserve bumps known as [[mammillae]]. Sometimes the embryo had absorbed so much of the calcium that the mammilae need a magnifying glass or [[microscope]] to be seen.<ref name="enbd-collecting-115" /> However, there are many kinds of naturally occurring objects which can resemble fossil eggs. These can fool even professional paleontologists.<ref name="enbd-fake-118" />
[[File:Zkamenělé vejce dinosaura z pouště Gobi, expozice Národního muzea v Praze (2007).jpg|thumb|left|Fossilized dinosaur egg from the Gobi desert, National Museum in Prague]]
===False eggs===
'''Calculus:''' Calculi are egg-like objects formed in the stomachs of [[ruminants]] such as [[cattle]], [[deer]], [[elk]], and [[goats]]. Calculus formation is a defense mechanism protecting the ruminant's stomach from damage if it swallows a foreign object while grazing. After ingestion, the object is covered by the same material composing bone, [[calcium phosphate]], and eventually vomited out of the animal's system. These "stomach stones" tend to range in size from 1 to 6 centimeters. Larger sizes are known but very rare.<ref name="enbd-fake-121" /> Sometimes tiny dimples cover the surface of a stomach stone, which can fool observers into thinking they are the pores of an egg.<ref name="enbd-fake-120" /> Fossil egg expert Ken Carpenter has described stomach stones as the most egg-like natural objects, noting that they are "the trickiest [egg-like] objects to correctly identify".<ref name="enbd-fake-120-121" /> Calculi are so egg-like that on one occasion a detailed description of a stomach stone misidentified as a fossil egg was published in the scientific literature.<ref name="enbd-fake-120" /> Calculi can be distinguished from real egg fossils because when they are broken open, they show the layers of calcium phosphate and the foreign object at the core.<ref name="enbd-fake-120" /> Multiple layers of eggshell are known in [[Egg paleopathology|pathological eggs]], but these layers don't go all the way down to its core the way a stomach stone's do. Calculi are often suspiciously intact, unlike fossil eggs, which are usually damaged.<ref name="enbd-fake-121" /> Stomach stones also lack distinct shells with their attending structural components like continuous or prismatic layers, mammillae, and pores.<ref name="enbd-fake-120" />
'''Concretions:''' [[Concretions]] are formed when decaying organisms change the chemistry of their immediate surroundings in a manner that is conducive to minerals [[precipitating]] out of solution. These minerals accumulate in a mass roughly shaped like the region of altered chemistry. Sometimes the {{Not a typo|mass produced}} is egg-shaped.<ref name="enbd-fake-119" /> Most egg-shaped concretions have uniform interiors, however some form through the accumulation of mineral in layers.<ref name="enbd-fake-119-120" /> These layered concretions can be even harder to recognize than those with uniform interiors because the layers can resemble egg white and yolk. The yellow of the false yolk comes from minerals like limonite, siderite, and sulfur.<ref name="enbd-fake-120" />
Concretions also generally lack distinct shells, although sometimes they can appear to have them if their outside surfaces have been case-hardened. Since their interiors are softer, erosion can separate the two, creating eggshell pseudofossils. Real egg fossils should preserve eggshell structures like pores, mammillae, and prismatic or continuous layers, which are not present in concretions. Any given concretion is unlikely to be exactly the same size as any other, so associations of egg-like objects of different sizes are probably not real eggs at all. Concretions can also be far larger than any real egg so an apparently unnaturally large "egg" has probably been misidentified.<ref name="enbd-fake-120" />
'''Insect trace fossils:''' Sometimes the living or breeding chambers of an insect burrow are so perfectly egg-shaped that even a paleontologist can mistake a natural cast of these chambers for a fossil egg. Insect burrow fossils can sometimes be distinguished from real egg fossils by the presence of "scratch marks" on their surface left by the insect during the burrow's original excavation. Fossil insect pupae can also resemble eggs. After death and burial, the decomposition of a deceased pupa would leave a gap in the sediment that could be filled with minerals carried by groundwater, forming an egg-like cast. These pseudo-eggs can be recognized by their small size (usually not much longer than a centimeter or two) and lack of an eggshell with its typical anatomy.<ref name="enbd-fake-120" />
'''Stones:''' The erosive effects of water can sometimes round rocks into egg-like shapes.<ref name="enbd-fake-119" />
==Structure==
Paleontologists' knowledge of the structure of dinosaur eggs is limited to the hard shell. However, it can be inferred that dinosaur eggs had an [[amnion]], [[chorion (egg)|chorion]], and an [[allantois]], the three major membranes in modern bird and reptile eggs. Dinosaur eggs vary greatly in size and shape, but even the largest dinosaur eggs (''[[Megaloolithus]]'') are smaller than the largest known bird eggs, which were laid by the extinct [[elephant bird]]. Dinosaur eggs range in shape from spherical to highly elongated (some specimens three times longer than they are wide). Some elongated eggs are symmetrical, whereas others have one rounded end and one pointed end (similar to bird eggs). Most elongated eggs were laid by theropods and have an avian-like eggshell, whereas the spherical eggs typically represent non-theropod dinosaurs.<ref name="Making an Egg">{{cite book|last1=Carpenter|first1=Kenneth|title=Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)|date=1999|publisher=Indiana University Press|location=Bloomington, Indiana|isbn=978-0-253-33497-8|pages=[https://archive.org/details/isbn_9780253334978/page/85 85–107]|chapter=Making an Egg|url=https://archive.org/details/isbn_9780253334978/page/85}}</ref>
[[File:Eggshell Structure diagram.jpg|thumb|240px|Diagram of a two-layered eggshell.]] Fossil dinosaur eggshells, like modern bird and reptile eggshells, are made up of [[calcium carbonate]] crystal units. The basic arrangement and structure of these eggshell units (called the ultrastructure) is used to divide fossil eggs into several basic types, including the spherulitic, prismatic, and ornithoid basic types, which contain dinosaurs.<ref name="How to Study">{{cite book|last1=Carpenter|first1=Kenneth|title=Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)|date=1999|publisher=Indiana University Press|location=Bloomington, Indiana|isbn=978-0-253-33497-8|pages=[https://archive.org/details/isbn_9780253334978/page/122 122–144]|chapter=How to Study a Fossil Egg|url=https://archive.org/details/isbn_9780253334978/page/122}}</ref> Dinosaur eggs further [[#Classification|classified]] by the microstructural aspects of the crystalline structure of the eggshell units and by the type of their pores and their shell ornamentation.<ref name="UCMP"/>
===Layers===
Dinosaur eggshells are divided into one, two, or three layers of distinct ultrastructure.<ref name="UCMP"/><ref>{{Cite journal|last=Dauphin|first=Y.|date=1990|title=Comparative microstructural studies of eggshells. 1. Dinosaurs of the Southern France|journal=Revue de Paléobiologie|volume=9|pages=127–133}}</ref><ref>{{Cite journal|last=Dauphin|first=Y.|date=1990|title=Incidence de l'état diagénétique des coquilles d'oeufs de dinosaures sur la reconnaissance des morphotypes - exemple du Bassin d'Aix en Provence|journal=C. R. Acad. Sci. Paris|volume=sér/ II, 310|pages=849–954}}</ref><ref>{{Cite journal|last1=Dauphin|first1=Y.|last2=Jaeger|first2=J.J.|date=1991|title=Implications de l'analyse microstructurale et géochimique des œufs de dinosaures de la cairanne (Bassin d'Aix en Provence, France, Rognacien inférieur)|journal=Paläontologische Zeitschrift|volume=65|issue=3–4|pages=391–404|doi=10.1007/bf02989853|s2cid=129041143|issn=0031-0220}}</ref>
The innermost layer, known as the mammillary layer or the cone layer, is only found in theropod eggs (the prismatic and ornithoid basic types). It is composed of cone-shaped structures called mammillae at the base of each shell unit. Mammillae are the first part of the eggshell to form. Each mammilla forms from crystals radiating outward from an organic core until they touch neighboring mammillae and grow upwards into the next layer.<ref name="Making an Egg"/><ref name="UCMP">Laura E. Wilson, Karen Chin, Frankie D. Jackson, and Emily S. Bray. [http://www.ucmp.berkeley.edu/science/eggshell/eggshell2.php II. Eggshell morphology and structure]. ''UCMP Online Exhibits: Fossil Eggshell''</ref> In spherulitic eggs, the eggs of non-theropod dinosaurs, the eggshell units grow upward from their organic cores; the base of each eggshell unit is rounded, but is not a true mammilla because it does not have a distinct ultrastructure from the top of the unit.<ref name="Making an Egg"/><ref name="How to Study"/>
The second layer is alternately called the prismatic layer, the columnar layer, the continuous layer, the crystalline layer,<ref name="Making an Egg"/> the cryptoprismatic layer,<ref name="Simon 2014">Simon, D. J. (2014). "[http://scholarworks.montana.edu/xmlui/bitstream/handle/1/8693/SimonD0814.pdf?sequence=1 Giant Dinosaur (theropod) Eggs of the Oogenus Macroelongatoolithus (Elongatoolithidae) from Southeastern Idaho: Taxonomic, Paleobiogeographic, and Reproductive Implications.]" (Doctoral dissertation, Montana State University, Bozeman).</ref> the palisade layer,<ref name="UCMP"/> the spongy layer,<ref name=M1996>{{cite journal |last=Mikhailov |first=Konstantin |date=1996 |title=Bird Eggs in the Upper Cretaceous of Mongolia |journal=Paleontological Journal |volume=30 |issue=1 |pages=114–116}}</ref> or the single layer.<ref name="Vianey-Liaud and Lopez-Martinez 1997">{{cite journal | last1 = Vianey-Liaud | first1 = Monique | last2 = Lopez-Martinez | first2 = Nieves | year = 1997 | title = Late Cretaceous Dinosaur Eggshells from the Tremp Basin, Southern Pyrenees, Lleida, Spain | journal = Journal of Paleontology | volume = 71 | issue = 6| pages = 1157–1171 | doi=10.1017/s002233600003609x| s2cid = 131405598 | url = https://eprints.ucm.es/id/eprint/69803/1/3Vianey%26LopezM97-1.pdf }}</ref> In this layer, the shell units can be distinct, partially fused together, or entirely continuous.<ref name="How to Study"/> In some dinosaur eggs, the prismatic layer exhibits squamatic ultrastructure, where the prismatic structure is obscured by a rough texture resembling lizard skin.<ref name="UCMP"/><ref name="How to Study"/>
Though rare in non-avian dinosaurs, some theropod eggs and most bird eggs have a third layer (known as the external layer) made up of vertical calcite crystals.<ref name="UCMP"/><ref name="Making an Egg"/>
===Pore canals===
In all eggs, the embryo must breathe. In egg-laying amniotes (including dinosaurs), pore canals cutting through the eggshell allow gas exchange between the embryo and the outside world. Dinosaur eggshells exhibit a lot of diversity in pore size, density, and shape. One early attempt at classification of dinosaurian eggs, proposed by the Soviet paleontologist A. Sochava, was based on grouping eggs by their pore systems.<ref name="Intro">{{cite book|last1=Carpenter|first1=Kenneth|last2=Hirsch|first2=Karl|last3=Horner|first3=John|editor1-last=Carpenter|editor1-first=Kenneth|editor2-last=Hirsch|editor2-first=Karl|editor3-last=Horner|editor3-first=John|title=Dinosaur Eggs and Babies|date=1994|publisher=University of Cambridge|location=Trumpington Street, Cambridge|isbn=978-0-521-44342-5|pages=1–11|chapter=Introduction}}</ref> This system was abandoned when it was discovered that different eggs could have very similar pores, but pore systems do play an important role in modern eggshell parataxonomy.<ref name="How to Study"/> The density and width of the pores, combined with the eggshell's thickness can be used to predict the [[gas conductance]] of a dinosaur's egg.<ref name="UCMP"/> This can provide both information about nesting behavior and about the climate: eggs buried in sediment have higher rates of gas conductance than those laid in the open, and eggs laid in arid environments have lower gas conductance (to prevent water loss) than those laid in more humid conditions.<ref name="UCMPV">Laura E. Wilson, Karen Chin, Frankie D. Jackson, and Emily S. Bray. [http://www.ucmp.berkeley.edu/science/eggshell/eggshell2.php V. Paleobiology and eggs]. ''UCMP Online Exhibits: Fossil Eggshell''</ref>
Paleontologist and fossil egg expert Kenneth Carpenter catalogued six types of pore systems:<ref name="How to Study"/>
#Angusticanaliculate - Long, narrow, straight pores with low pore density. These eggs would have a low gas exchange rate, and therefore they were typically laid in dry areas.<ref name="How to Study"/>
#Tubocanaliculate - Large diameter pores with funnel-shaped openings on both inner and outer surfaces of the shell. These eggs would have a high gas exchange rate, and therefore were probably buried in humid mounds.<ref name="How to Study"/>
#Multicanaliculate - Numerous large, branching, and closely spaced pore canals. They have a high gas exchange rate, so like tubocanaliculate eggs they were probably also buried humid mounds.<ref name="How to Study"/>
#Prolatocanaliculate - Pores vary in width throughout their length. Gas exchange water loss rates are variable, so these eggs could have been laid in many different environments. This type is subdivided into foveocanaliculate with larger pore openings, and lagenocanaliculate with narrower pore openings.<ref name="How to Study"/>
#Rimocanaliculate - Very narrow slitlike pore canals. This pore system is seen in modern ostriches, so these eggs were laid in open nests, similar to how ostriches do today.<ref name="How to Study"/>
#Obliquicanaliculate - These canals cut diagonally through multiple eggshell units instead of going between them like in other pore systems. Obliquicanaliculate pores are only found in a single oogenus: ''[[Preprismatoolithus]]''.<ref name="How to Study"/>
===Ornamentation===
Unlike most modern eggs, many dinosaur eggs had a rough texture formed by nodes and ridges ornamenting the surface of their shell.<ref name="UCMP"/> This is predominant in Cretaceous dinosaur eggs, but very rare in eggs from the Jurassic or Triassic.<ref name="Nests">{{cite book|last1=Moratalla|first1=J.J.|last2=Powell|first2=J.E.|editor1-last=Carpenter|editor1-first=Kenneth|editor2-last=Hirsch|editor2-first=Karl|editor3-last=Horner|editor3-first=John|title=Dinosaur Eggs and Babies|date=1994|publisher=Cambridge University Press|location=The Pitt Building, Trumpington Street, Cambridge|pages=37–46|chapter=Dinosaur Nesting Patterns}}</ref> Because of the lack of modern analogues, the purpose of eggshell ornamentation is unknown,<ref name="UCMP"/> but many functions have been proposed.<ref name="Nests"/> Possibly, they provided extra strength to the eggshell without having pore canals too long for adequate gas exchange. They could also have helped keep substrate away from the pore openings of eggs that were buried, but modern [[turtle]]s and [[crocodylian]]s which bury their eggs have smooth eggshells, so this adaptation is not necessary for animals which bury their eggs. Another hypothesis, proposed by R. M. Mellon in [[1982 in paleontology|1982]] in his [[senior thesis]] at [[Princeton University]], is that the ridges and nodes would have formed pathways for gas to flow across the surface of the eggshell, preventing accumulation of too much [[Carbon dioxide|CO<sub>2</sub>]] and aiding the flow of oxygen and water vapor.<ref name="Nests"/>
Since it varies from egg to egg, the texture of an eggshell's ornamentation is useful for classification. Six types of ornamentation were catalogued by Carpenter in 1999:<ref name="How to Study"/>
#Compactituberculate - The dome-shaped tops of the shell units form a dense covering of nodes on the surface of the eggshell. This type of ornamentation is most commonly seen in [[Megaloolithidae|megaloolithids]].<ref name="Soto">{{cite journal | last1 = Soto | first1 = M. | last2 = Perea | first2 = D. | last3 = Cambiaso | first3 = A.V. | year = 2012 | title = First sauropod (Dinosauria: Saurischia) remains from the Guichón Formation, Late Cretaceous of Uruguay | url = https://www.researchgate.net/publication/232399931 | journal = Journal of South American Earth Sciences | volume = 33 | issue = 1| pages = 68–79 | doi = 10.1016/j.jsames.2011.08.003 | bibcode = 2012JSAES..33...68S }}</ref>
#Sagenotuberculate - The nodes and ridges form a netlike pattern interspersed with pits and grooves.
#Dispersituberculate - Scattered nodes. This ornamentation is seen on the poles of elongated eggs, which may have allowed accumulations CO<sub>2</sub> at the poles to escape between the nodes.<ref name="Nests"/>
#Lineartuberculate - Ridges, and chains of ridges and nodes form lines parallel to the long axis of the egg.
#Ramotuberculate - Irregular chains of nodes, typically found as a transition between the lineartuberculate midsection and dispersituberculate ends of elongated eggs.
#Anastomotuberculate - Ridges similar to lineartuberculate, but instead form wavy, branching, or [[anastomosing]] patterns resembling the water ripple marks in sand.
==Classification==
The classification of dinosaur eggs is based on the structure of the egg shells viewed in thin section via microscope, although new techniques such as electron backscatter diffraction have been used.<ref>{{cite journal|journal=[[PLOS ONE]]|volume=11|issue=5|last1=Moreno-Azanza|first1=Miguel|last2=Bauluz|first2=Blanca|last3=Canudo|first3=José Ignacio|last4=Gasca|first4=José Manuel|last5=Fernández-Baldor|first5=Fidel Torcida|title=Combined Use of Electron and Light Microscopy Techniques Reveals False Secondary Shell Units in Megaloolithidae Eggshells|publication-date=May 4, 2016|doi=10.1371/journal.pone.0153026|pmid=27144767|year=2016|page=e0153026|bibcode=2016PLoSO..1153026M|pmc=4856302|doi-access=free}}</ref> There are three main categories of dinosaur eggs: spherulitic (sauropods and [[Hadrosaurid|hadrosaurs]]),<ref name="basic-spherulitic-136-137" /> [[Prism (geometry)|prismatic]],<ref name="basic-prismatic-137" /> and ornithoid ([[Theropoda|theropods]], including modern birds).<ref name=ubristol/>
===Oogenera===
[[Oogenus|Oogenera]] are taxonomic names for types of eggshell. Nearly three dozen oogenera have been named for dinosaur eggs:
[[File:Segnosaurus nest 2.jpg|thumb|[[Therizinosaur]] nest and eggs (''[[cf.]]'' ''[[Segnosaurus]]'') in from ''[[Dinosaurland]]'' in [[Lyme Regis]], England.]]
{{div col|colwidth=20em}}
* ''[[Ageroolithus]]''
* ''[[Apheloolithus]]''<ref name=DFG03 />
* ''[[Boletuoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=82906 The Palaeobiology Database]</ref>
* ''[[Cairanoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67205 The Palaeobiology Database]</ref>
* ''[[Continuoolithus]]''<ref name=DFG03/>
* ''[[Dendroolithus]]''<ref name=DFG03/>
* ''[[Dictyoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67198 The Palaeobiology Database]</ref>
* ''[[Dispersituberoolithus]]''
* ''[[Ellipsoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=81056 The Palaeobiology Database]</ref>
* ''[[Elongatoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67185 The Palaeobiology Database]</ref>
* ''[[Faveoolithus]]''<ref name=DFG03 />
* ''[[Heishanoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=81709 The Palaeobiology Database]</ref>
* ''[[Laevisoolithus]]''
* ''[[Macroolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67183 The Palaeobiology Database]</ref>
* ''[[Macroelongatoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=98798 The Palaeobiology Database]</ref>
* ''[[Megaloolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=65584 The Palaeobiology Database]</ref>
* ''[[Nanshiungoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67189 The Palaeobiology Database]</ref>
* ''[[Oblongoolithus]]''
* ''[[Ovaloolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=56741 The Palaeobiology Database]</ref>
* ''[[Pachycorioolithus]]''<ref name="Lawver et al 2016">{{cite journal|last1=Lawver|first1=Daniel R.|last2=Jin|first2=Xingsheng|last3=Jackson|first3=Frankie D.|last4=Wang|first4=Qiongying|title=An Avian Egg from the Lower Cretaceous (Albian) Liangtoutang Formation of Zhejiang Province, China|journal=Journal of Vertebrate Paleontology|date=2016|volume=36|issue=3|page=e1100631|doi=10.1080/02724634.2016.1100631|s2cid=88169746}}</ref>
* ''[[Paraspheroolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67196 The Palaeobiology Database]</ref>
* ''[[Phaceloolithus]]''<ref name=DFG03/>
* ''[[Placoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=68519 The Palaeobiology Database]</ref>
* ''[[Porituberoolithus]]''
* ''[[Polyclonoolithus]]''<ref name="Xie et al 2016">{{cite journal | last1 = Xie | first1 = J.-F. | last2 = Zhang | first2 = S.-K. | last3 = Jin | first3 = X.-S. | last4 = Li | first4 = D.-Q. | last5 = Zhou | first5 = L.-Q. | year = 2016 | title = A new type of dinosaur eggs from Early Cretaceous of Gansu Province, China | url = http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201512/P020151203499501638411.pdf | journal = Vertebrata PalAsiatica | volume = 54 | issue = 1 | pages = 1–10 | access-date = January 11, 2016 | archive-url = https://web.archive.org/web/20160129003559/http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201512/P020151203499501638411.pdf | archive-date = January 29, 2016 | url-status = dead }}</ref>
* ''[[Preprismatoolithus]]''<ref name=DFG03/>
* ''[[Prismatoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=65562 The Palaeobiology Database]</ref>
* ''[[Protoceratopsidovum]]''<ref name="The Palaeobiology Database">[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=84312 The Palaeobiology Database]</ref>
* ''[[Pseudogeckoolithus]]''
* ''[[Shixingoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67195 The Palaeobiology Database]</ref>
* ''[[Sphaerovum]]''<ref name=DFG03/>
* ''[[Spheroolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67290 The Palaeobiology Database]</ref>
* ''[[Spheruprismatoolithus]]''<ref name="The Palaeobiology Database"/>
* ''[[Stromatoolithus]]''<ref name=DFG03/>
* ''[[Subtiliolithus]]''<ref name=DFG03/>
* ''[[Tacuarembovum]]''<ref name=DFG03/>
* ''[[Trachoolithus]]''<ref>[http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=81708 The Palaeobiology Database]</ref>
* ''[[Tristraguloolithus]]''
* ''[[Youngoolithus]]''<ref name=DFG03/>
{{div col end}}
===Embryos===
Dinosaur embryos, the animal inside the eggs, are very rare but useful to understand [[ontogeny]], [[heterochrony]], and dinosaur [[systematics]].
Embryo fossils are known from:
{{div col|colwidth=20em}}
* ''[[Beibeilong]]''
* ''[[Citipati (dinosaur)|Citipati]]''<ref>{{cite journal | last1 = Norell | first1 = M. A. | last2 = Clark | first2 = J. M. | last3 = Dashzeveg | first3 = D. | last4 = Barsbold | first4 = T. | last5 = Chiappe | first5 = L. M. | last6 = Davidson | first6 = A. R. | last7 = McKenna | first7 = M. C. | last8 = Novacek | first8 = M. J. | year = 1994 | title = A theropod dinosaur embryo, and the affinities of the Flaming Cliffs Dinosaur eggs | journal = Science | volume = 266 | issue = 5186| pages = 779–782 | doi=10.1126/science.266.5186.779| pmid = 17730398 | bibcode = 1994Sci...266..779N | s2cid = 22333224 }}</ref>
* ''[[Heyuannia]]''
* ''[[Lufengosaurus]]''
* ''[[Lourinhanosaurus]]''<ref name="mateus-et-al" /><ref name="dericqles-et-al" />
* ''[[Massospondylus]]''<ref name="reisz-et-al" />
* ''[[Maiasaura]]''
* ''[[Troodon]]''<ref name="horner-weishampel" />
{{div col end}}
==Taphonomy==
{{Main|Egg taphonomy}}
The formation of fossil eggs begins with the original egg itself. Not all eggs that end up fossilizing experience the death of their embryo beforehand. Fossil eggs with open tops are common and could result from the preservation of eggs that hatched successfully.<ref name="enbd-fossilize-112" /> Dinosaur eggs whose embryos died were likely victims of similar causes to those that kill embryos in modern reptile and bird eggs. Typical causes of death include congenital problems, diseases, [[suffocation]] from being buried too deep, inimical temperatures, or too much or too little water.<ref name="enbd-fossilize-113" />
Whether or not hatching was successful, burial would begin with sediments gradually entering any large openings in the shell.<ref name="enbd-fossilize-112" /> Even intact eggs are likely to fill with sediment once they crack under the strain of deep burial. Sometimes, though, fossilization can begin fast enough to prevent the eggs from being cracked. If the water table is high enough dissolved minerals like calcite can percolate through the pores of the eggshell. When the egg is completely filled it can become sturdy enough to withstand the weight of the overlying sediments.<ref name="enbd-fossilize-113" /> Not all fossil egg specimens are of complete specimens, however. Individual pieces of eggshell are much more robust than the entire egg and can be transported intact long distances from where they were originally laid.<ref name="enbd-fossilize-108" />
When the egg is buried deeply enough, the bacteria decomposing it no longer have access to oxygen and need to power their metabolisms with different substances. These physiological changes in the decomposers also alter the local environment in a way that allows certain minerals to be deposited, while others remain in solution.<ref name="enbd-fossilize-113" /> Generally, however, a fossilizing egg's shell keeps the same calcite it had in life, which allows scientists to study its original structure millions of years after the developing dinosaur hatched or died.<ref name="enbd-fossilize-114" /> However, eggs can also sometimes be altered after burial. This process is called [[diagenesis]].<ref name="enbd-fossilize-114" /> One form of diagenesis is a microscopic [[Hatching#Variations|cross-hatched]] pattern imposed on the eggshell by the pressure of being buried deeply.<ref name="enbd-fossilize-114-115" /> If the pressure gets severe enough, sometimes the eggshell's internal microscopic structure can be completely destroyed. Diagenesis can also happen chemically in addition to physically. The chemical conditions of a decomposing egg can make it easy for silica to be incorporated into eggshell and damage its structure. When iron-bearing substances alter eggshell it can be obvious because compounds like [[hematite]], [[pyrite]], and [[iron sulfide]] can turn the shell blackish or rusty colors.<ref name="enbd-fossilize-115" />
===Depositional environments===
Dinosaur eggs are known from a variety of depositional environments.
'''[[Beach sands]]:''' Beach sands were a good place for dinosaurs to lay their eggs because the sand would be effective at absorbing and holding enough heat to incubate the eggs. One ancient beach deposit in northeastern Spain actually preserves about 300,000 fossil dinosaur eggs.<ref name="enbd-fossilize-111" />
'''[[Floodplains]]:''' Dinosaurs often laid their eggs on ancient floodplains. The [[mudstone]]s deposited at these sites are therefore excellent sources of dinosaur egg fossils.<ref name="enbd-fossilize-108" />
'''[[Sand dunes]]:''' Many dinosaur eggs have been recovered from sandstone deposits that formed in the ancient dune fields of what are now northern China and Mongolia.<ref name="enbd-fossilize-110" /> The presence of ''[[Oviraptor]]'' preserved in their life brooding position suggests that the eggs, nests, and parents may have been rapidly buried by sandstorms.<ref name="enbd-fossilize-111" />
==Excavation and preparation==
Usually the first evidence of fossil dinosaur eggs to be discovered are shell fragments that have eroded away from the original eggs and been transported downhill by the elements.<ref name="enbd-collecting-115" /> If the source eggs can be found the area must be examined for more unexposed eggs. If the paleontologists are fortunate enough to have found a nest, the number and arrangement of the eggs must be estimated. Excavation must proceed to significant depth since many dinosaur nests include multiple layers of eggs. As the underside of the nest is excavated, it would be covered by material like newspaper, tin foil, or tissue. Afterwards, the entire block is covered in multiple layers of plaster-soaked strips of burlap. When the plaster is dried, the block is undercut the rest of the way and turned over.<ref name="enbd-collecting-117" />
The fine work of cleaning the egg fossils is performed in a laboratory. Preparation usually begins from the underside of the block, which tends to be the best preserved.<ref name="enbd-collecting-117" /> Because of their fragility, cleaning fossil eggs requires patience and skill.<ref name="enbd-collecting-117-118" /> Scientists use delicate instruments like dental picks, needles, small [[pneumatic]] engraving tools, and [[X-Acto]] knives.<ref name="enbd-collecting-117" /> Scientists must determine at what point to stop cleaning based on their own criteria. If eggs are fully extracted they can be more fully studied individually at the cost of information regarding the spatial relationships between eggs or if the eggs had hatched. Commercial fossil dealers tend to expose only the bottom of the eggs since the topsides might be damaged by hatching and therefore less visually appealing to potential customers.<ref name="enbd-collecting-118" />
==Research techniques==
===Acid dissolution===
Acids can be used to learn more about fossil eggs. Diluted [[acetic acid]] or [[EDTA]] can be used to expose the microstructure of shell that has been damaged by weathering. Acids are also used to extract embryo skeletons from the egg encasing them.<ref name="enbd-tools-128" /> Even fossilized soft tissue like muscle and cartilage as well as fat globules from the original [[egg yolk]] can be uncovered using this method.<ref name="enbd-tools-130" /> Amateur paleontologist [[Terry Manning]] has been credited with groundbreaking work developing this technique.<ref>https://embryo.asu.edu/pages/acid-dissolution-fossil-dinosaur-eggs Last paragraph</ref> First, the paleontologist must submerge the egg in a very dilute phosphoric acid bath. Since the acid solution can penetrate the egg, every few days the specimen must be soaked in distilled water to prevent the acid from damaging the embryo before it is even exposed. If embryonic fossil bone is revealed after drying from the water bath, the exposed fossils must be delicately cleaned with fine instruments like needles and paint brushes. The exposed bone is then coated with plastic preservatives like [[Acryloid B67]], [[Paraloid B72]], or [[Vinac B15]] to protect it from the acid when submerged for another round. The complete process can take months before the whole embryo is revealed.<ref name="enbd-tools-128" /> Even then only about 20% of the eggs subjected to the process reveal any embryo fossils at all.<ref name="enbd-tools-128-130" />
===CAT scans===
[[CAT scans]] can be used to infer the 3D structure of a fossil egg's interior by compiling images taken of slices through the egg in small regular increments. Scientists have tried to use CAT scans to look for embryo fossils contained inside the egg without having to damage the egg itself by physically extracting them. However, as of Ken Carpenter's 1999 book on dinosaur eggs, ''Eggs, Nests, and Baby Dinosaurs'', all alleged embryos discovered using this method were actually false alarms. Variations in the type of infilling mineral or cement binding the infilling sediment into rock sometimes resemble bones in CAT scan images. Sometimes eggshell fragments that fell back into the egg when it hatched have been mistaken for embryonic bones.<ref name="enbd-tools-128" /><ref name="enbd-collecting-7-11" /> The use of CAT scans to search for embryonic remains is actually conceptually flawed since embryonic bones have not yet [[Ossification|mineralized]]. Since the infilling sediment is their only source of minerals they will be preserved at basically the same density and therefore have poor visibility in the scan. The validity of this issue has been confirmed by performing Cat scans on fossil eggs known to have embryos inside and noting their poor visibility in the scan images. The only truly reliable way to discover a dinosaur embryo is to cut the egg open or dissolve some of its eggshell away.<ref name="enbd-tools-128" />
===Cathodoluminescence===
[[Cathodoluminescence]] is the most important tool paleontologists have for revealing whether or not the [[calcium]] in fossil eggshell has been altered.<ref name="enbd-tools-133" /> Calcite in eggshell is either pure or rich in [[calcium carbonate]]. However, the calcite composing the egg can be altered after burial to include significant calcium content. Cathodoluminescence causes calcite altered in this fashion to glow orange.<ref name="enbd-tools-134" />
===Gel electrophoresis===
[[Gel electrophoresis]] has been used in attempts to identify the [[amino acids]] present in the organic components of dinosaur eggshell. Contact with human skin can contaminate eggs with foreign amino acids, so only untouched eggs can be investigated using this technique. [[EDTA]] can be used to dissolve the calcite of the eggshell while leaving the shell's organic content intact. The resultant organic residue would be blended and then implanted into [[gel]]. Electricity would then be run through the sample, causing the amino acids to migrate through the gel until they stop at levels determined by their physical properties. [[Protein silver stain]] is then used to dye the amino acids and make them visible.<ref name="enbd-tools-133" /> The bands of amino acids from the dinosaur eggs can then be compared with the banding of samples with known composition for identification.<ref name="enbd-tools-133" />
Gel electrophoresis is not necessarily a perfect means of discovering the amino acid composition of dinosaur eggshell because sometimes the amount or type of amino acids present could be altered during or after preservation. One potential confounding factor would be the heating of deeply buried egg fossils, which can break down amino acids. Another potential source of error is groundwater, which can leach away amino acids. These issues cast doubt as to whether the results these sorts of studies give are reliable as the actual composition of the eggshell's organic material in life. However, studies applying these techniques have made suggestive findings, including amino acid profiles in dinosaur eggs similar to those in modern birds.<ref name="enbd-tools-133" />
===Geneva lens measure===
The [[Geneva Lens Measure]] is a device used to measure curved surfaces. It is most commonly used by [[opticians]] to measure lenses but can also be used by paleontologists to estimate the life size of dinosaur eggs from shell fragments. The instrument can be used to help estimate the size of fossil eggshells by measuring their curved surfaces. Since most eggs aren't perfectly round measurements from multiple parts of the egg with varying shell curvatures may be needed to get a full idea of the egg's size. Ideally an eggshell fragment being used to estimate the full size of an egg should be more than 3 cm long. Smaller eggshell fragments are better suited to other methods of study, like the [[Obrig radius dial gauge]]. The Geneva Lens measure gives units in [[diopters]] which must be converted to the radius in millimeters. Use of the Geneva Lens Measure to estimate the size of a fossil egg was first done by [[Sauer]] on fossil ostrich eggs.<ref name="enbd-tools-134" />
===Light microscopy===
[[Light microscopy]] can be used to magnify the structure of dinosaur eggshell for scientific research. To do so an eggshell fragment must be embedded in [[epoxy]] [[resin]] and sliced into a thin section with a thin-bladed [[rock saw]]. This basic method was invented by French paleontologist [[Paul Gervais]] and has remained almost unchanged ever since. Horizontally cut thin sections are called tangential thin sections while vertically cut thin sections are called radial sections. Regardless of direction, the sample must be abraded by fine-grit [[Sand paper|sand]] or [[emery paper]] until it is [[translucent]]. Then the structure of the shell's [[calcite|calcite crystals]] or pores can be examined under a [[petrographic microscope]].<ref name="enbd-tools-122" /> The calcite crystal structure of dinosaur eggshell can be classified by their effect on [[polarized light]]. Calcite is capable of acting as a polarizing light filter.<ref name="enbd-tools-124" /> When a microscopic thin section sample is rotated relative to polarized light it can eventually block all the light and seem opaque. This phenomenon is called extinction. Different varieties of dinosaur eggs with their different calcite crystal structures have different light extinction properties that can be used to identify and distinguish even eggs that seem very similar on the surface.<ref name="enbd-tools-125" /> To reconstruct the three-dimensional structures of the shell's pore channels scientists require a series of multiple radial sections.<ref name="enbd-tools-122" />
===Scanning electron microscopy===
[[Scanning electron microscopy]] is used to view dinosaur eggshell under even greater magnification than is possible with light microscopy. However, this does not mean that scanning electron microscopy is necessarily the superior research method. Since both techniques provide differing amounts and types of information they can be used together synergistically to provide a more complete understanding of the specimen under scrutiny. Eggshell specimens best suited for scanning electron microscopy are those recently broken because such a break will usually occur along the plane of the eggshell's calcite crystal lattice. First, a small specimen would be covered with a very thin layer of [[gold]] or [[platinum]]. The specimen would then be bombarded with [[electrons]]. The electrons bounce back off the metal and due to their small size, can be used to form a detailed image of the specimen.<ref name="enbd-tools-125" />
===Mass spectrometry===
[[Mass spectrometry]] is a method for determining eggshell composition that uses a device called a mass spectrometer. First, the eggshell sample must be powdered and placed in the mass spectrometer's vacuum chamber.<ref name="enbd-tools-130" /> The powder is vaporized by the heat of an intense laser beam. A stream of electrons then bombard the gaseous eggshell molecules, which breaks down the molecules in the eggshell and imbues them with a positive charge. A magnetic field then sorts them by mass before they are detected by the spectrometer.<ref name="enbd-tools-131" /> One application of mass spectrometry has been to study the isotope ratios of dinosaur eggshell in order to ascertain their diets and living conditions. However this research is complicated by the fact that isotope ratios can be altered post mortem before or during fossilization. Bacterial decomposition can alter [[carbon isotope]] ratios in eggs and [[groundwater]] can alter the [[oxygen isotope]] ratios of eggshell.<ref name="enbd-tools-132" />
===X rays===
X-ray equipment, like CAT scans, are used to study the interior of fossil eggs. Unlike CAT scans, x-ray imaging condenses the entire interior of the egg into a single two-dimensional image rather than a series of images documenting the interior in three dimensions. X-ray imaging in the context of dinosaur research has generally been used to look for evidence of embryonic fossils contained inside the egg. However, as of Kenneth Carpenter's 1999 book ''Eggs, Nests, and Baby Dinosaurs'', all putative embryos discovered using x-rays have been misidentifications. This is because the use of x-rays to find embryos is conceptually flawed. Embryo bones are incompletely developed and will generally lack their own mineral content, as such the only source of minerals for these bones is the sediment that fills the egg after burial. The fossilized bones will therefore have the same density as the sediment filling the interior of the egg which served as the source for their mineral content and will be poorly visible in an x-ray image. So far the only reliable method for examining embryonic fossils preserved in dinosaur eggs is to physically extract them through means such as acid dissolution.<ref name="enbd-tools-128" />
X-rays can be used to chemically analyze dinosaur eggshell. This technique requires pure shell samples, so the fossil must be completely free of its surrounding rock matrix. The shell must then be further cleaned by an [[ultrasonic cleaning|ultrasonic bath]]. The sample can then be bombarded by electrons emitted by the same sort of probe used by scanning electron microscopes. Upon impact with the samples x-rays are emitted that can be used to identify the composition of the shell.<ref name="enbd-tools-130" />
[[X-ray diffraction]] is a method for determining eggshell composition that uses X-rays to directly bombard powdered eggshell. Upon impact some of the x-rays will be diffracted at different angles and intensities depending on the specific elements present in the eggshell.<ref name="enbd-tools-130" />
'''Allosterics'''
In order to test out how allosterics played a part in dinosaur egg size, scientists used modern day animal species such as birds, crocodiles, and tortoises in their experiment. They set the bird group as representing the theropods with the reptiles representing the sauropod group. The laid eggs of each species where compared with one another over the course of the study as well as against the fossilized eggs. The results that was retrieved from the experiment was that while sauropods laid smaller eggs in greater amounts each year, dinosaur of the theropod group was revealed to lay larger eggs less frequently over the years, similar to modern birds today.
==Footnotes==
{{Reflist|3|refs=
<ref name=ubristol>{{Citation
| title = What are dinosaur eggs?
| url = http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html
| archive-url = https://web.archive.org/web/20140201213751/http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html
| archive-date = February 1, 2014
| url-status = dead
}}</ref>
<ref name="mateus-et-al">Mateus et al. (1998).</ref>
<ref name="dericqles-et-al">de Ricqles et al. (2001).</ref>
<ref name="DFG03">Glut (2003).</ref>
<ref name="enbd-tools-122">"Tools of the Trade," Carpenter (1999); page 122.</ref>
<ref name="enbd-tools-124">"Tools of the Trade," Carpenter (1999); page 124.</ref>
<ref name="enbd-tools-125">"Tools of the Trade," Carpenter (1999); page 125.</ref>
<ref name="enbd-tools-128">"Tools of the Trade," Carpenter (1999); page 128.</ref>
<ref name="enbd-tools-128-130">"Tools of the Trade," Carpenter (1999); pages 128–130.</ref>
<ref name="enbd-tools-130">"Tools of the Trade," Carpenter (1999); page 130.</ref>
<ref name="enbd-tools-131">"Tools of the Trade," Carpenter (1999); page 131.</ref>
<ref name="enbd-tools-132">"Tools of the Trade," Carpenter (1999); page 132.</ref>
<ref name="enbd-tools-133">"Tools of the Trade," Carpenter (1999); page 133.</ref>
<ref name="enbd-tools-134">"Tools of the Trade," Carpenter (1999); page 134.</ref>
<ref name="enbd-collecting-115">"Collecting Eggs," Carpenter (1999); page 115.</ref>
<ref name="enbd-collecting-117">"Collecting Eggs," Carpenter (1999); page 117.</ref>
<ref name="enbd-collecting-117-118">"Collecting Eggs," Carpenter (1999); pages 117–118.</ref>
<ref name="enbd-collecting-118">"Collecting Eggs," Carpenter (1999); page 118.</ref>
<ref name="enbd-collecting-7-11">"Fig 7.11," Carpenter (1999); page 118.</ref>
<ref name="enbd-fake-118">"Fake Eggs," Carpenter (1999); page 118.</ref>
<ref name="enbd-fake-119">"Fake Eggs," Carpenter (1999); page 119.</ref>
<ref name="enbd-fake-119-120">"Fake Eggs," Carpenter (1999); pages 119–120.</ref>
<ref name="enbd-fake-120">"Fake Eggs," Carpenter (1999); page 120.</ref>
<ref name="enbd-fake-120-121">"Fake Eggs," Carpenter (1999); pages 120–121.</ref>
<ref name="enbd-fake-121">"Fake Eggs," Carpenter (1999); page 121.</ref>
<ref name="enbd-fossilize-108">"How to Fossilize an Egg," Carpenter (1999); page 108.</ref>
<ref name="enbd-fossilize-110">"How to Fossilize an Egg," Carpenter (1999); page 110.</ref>
<ref name="enbd-fossilize-111">"How to Fossilize an Egg," Carpenter (1999); page 111.</ref>
<ref name="enbd-fossilize-112">"How to Fossilize an Egg," Carpenter (1999); page 112.</ref>
<ref name="enbd-fossilize-113">"How to Fossilize an Egg," Carpenter (1999); page 113.</ref>
<ref name="enbd-fossilize-114">"How to Fossilize an Egg," Carpenter (1999); page 114.</ref>
<ref name="enbd-fossilize-114-115">"How to Fossilize an Egg," Carpenter (1999); pages 114–115.</ref>
<ref name="enbd-fossilize-115">"How to Fossilize an Egg," Carpenter (1999); page 115.</ref>
<ref name="horner-weishampel">"Correction: A comparative embryological study of two ornithischian dinosaurs," Horner and Weishampel (1996); page 103.</ref>
<ref name="reisz-et-al">"Abstract," Reisz et al. (2005); page 761.</ref>
<ref name="basic-spherulitic-136-137">"Basic Types Eggshell: Spherulitic Basic Type," Carpenter (1999); pages 136-137.</ref>
<ref name="basic-prismatic-137">"Basic Types Eggshell: Prismatic Basic Type," Carpenter (1999); page 137.</ref>
<ref name="enbd-first-1">"First Discoveries," Carpenter (1999); page 1.</ref>
<!-- Not in use
<ref name="enbd-classification-148-149">"Growth of the Modern Classification System," Carpenter (1999); pages 148-149.</ref>
<ref name="enbd-classification-149">"Growth of the Modern Classification System," Carpenter (1999); page 149.</ref>
Not in use-->
}}
==References==
* Carpenter, Kenneth (1999). ''Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)'', Indiana University Press; {{ISBN|0-253-33497-7}}.
* Deeming, D. C. and M. W. J. Ferguson (eds.) 1991. Egg incubation: its effect on embryonic development in birds and reptiles. Cambridge University Press, UK. 448pp.
* {{Citation |last=Glut |first=Donald F. |title=Dinosaurs: The Encyclopedia. 3rd Supplement |year=2003 |publisher=McFarland & Company, Inc. |location=Jefferson, North Carolina |isbn=978-0-7864-1166-5 |chapter=Appendix: Dinosaur Tracks and Eggs |pages=[https://archive.org/details/dinosaursencyclo00glut_2/page/613 613–652] |chapter-url=https://archive.org/details/dinosaursencyclo00glut_2/page/613 }}
* {{cite journal | last1 = Horner | first1 = John R. | last2 = Weishampel | first2 = David B. | year = 1996 | title = A comparative embryological study of two ornithischian dinosaurs - a correction | journal = Nature | volume = 383 | issue = 6595| pages = 256–257 | doi = 10.1038/383103b0 | doi-access = free | bibcode = 1996Natur.383..103H }}
* {{cite journal | last1 = Mateus | first1 = I | last2 = Mateus | first2 = H | last3 = Antunes | first3 = MT | last4 = Mateus | first4 = O | last5 = Taquet | first5 = P | last6 = Ribeiro | first6 = V | last7 = Manuppella | first7 = G | year = 1998 | title = Upper Jurassic theropod dinosaur embryos from Lourinhã (Portugal) | journal = Memórias da Academia das Ciências de Lisboa | volume = 37 | pages = 101–110 }}
* Moskvitch, Katia. [https://www.bbc.co.uk/news/science-environment-11734616 "Eggs with the Oldest Known Embryos of a Dinosaur Found"]. BBC News. November 12, 2010.
* {{cite journal | last1 = de Ricqlès | first1 = A. | last2 = Mateus | first2 = O. | last3 = Antunes | first3 = M. T. | last4 = Taquet | first4 = P. | year = 2001 | title = Histomorphogenesis of embryos of Upper Jurassic theropods from Lourinhã (Portugal) | journal = Comptes Rendus de l'Académie des Sciences, Série IIA | volume = 332 | issue = 10| pages = 647–656 | doi=10.1016/s1251-8050(01)01580-4| bibcode = 2001CRASE.332..647D }}
* {{cite journal | last1 = Reisz | first1 = Robert R. | last2 = Scott | first2 = Diane | last3 = Sues | first3 = Hans-Dieter | last4 = Evans | first4 = David C. | last5 = Raath | first5 = Michael A. | year = 2005 | title = Embryos of an Early Jurassic prosauropod dinosaur and their evolutionary significance | journal = Science | volume = 309 | issue = 5735| pages = 761–764 |bibcode = 2005Sci...309..761R | doi=10.1126/science.1114942 | pmid = 16051793| s2cid = 37548361 | url = http://doc.rero.ch/record/14975/files/PAL_E2124.pdf }}
* Skinner, Justin.[http://www.insidetoronto.com/news/local/article/812684--rom-puts-oldest-dinosaur-eggs-ever-discovered-on-display "ROM Puts Oldest Dinosaur Eggs Ever Discovered on Display"]. insidetoronto.com. May 6, 2010.
* {{Citation
| work = University of Bristol Earth Sciences
| title = What are dinosaur eggs?
| url = http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html
| access-date = June 20, 2013
| archive-url = https://web.archive.org/web/20140201213751/http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html
| archive-date = February 1, 2014
| url-status = dead
}}
==External links==
{{Portal|Dinosaurs}}
* {{Commons category-inline|Dinosauria eggs}}
{{Eggs}}
{{Authority control}}
[[Category:Eggs]]
[[Category:Dinosaur trace fossils]]
[[Category:Dinosaur reproduction]]' |
Unified diff of changes made by edit (edit_diff) | '@@ -2,13 +2,9 @@
{{Use mdy dates|date=July 2013}}
[[File:Indroda eggs.JPG|thumb|160px|Fossilized [[sauropod]] eggs displayed at [[Indroda Dinosaur and Fossil Park]]]]
-
-'''Dinosaur eggs''' are the organic vessels in which a [[dinosaurs|dinosaur]] embryo develops. When the first scientifically documented remains of non-avian dinosaurs were being described in [[England]] during the 1820s, it was presumed that dinosaurs had laid [[egg (biology)|eggs]] because they were [[reptiles]].<ref name="enbd-first-1" /> In 1859, the first scientifically documented dinosaur egg fossils were discovered in [[France]] by Jean-Jacques Poech, although they were mistaken for giant [[bird eggs]] ([[birds]] were not yet recognized as dinosaurs at the time).
-
-The first scientifically recognized non-avian dinosaur egg fossils were discovered in 1923 by an [[American Museum of Natural History]] crew in [[Mongolia]]. Dinosaur eggshell can be studied in [[thin section]] and viewed under a [[microscope]]. The interior of a dinosaur egg can be studied using [[CAT scans]] or by gradually dissolving away the shell with [[acid]]. Sometimes the egg preserves the remains of the developing [[embryo]] inside. The oldest known dinosaur eggs and embryos are from ''[[Massospondylus]]'', which lived during the [[Early Jurassic]], about 190 million years ago.<ref name="skinner">Skinner, Justin.[http://www.insidetoronto.com/news/local/article/812684--rom-puts-oldest-dinosaur-eggs-ever-discovered-on-display "ROM Puts Oldest Dinosaur Eggs Ever Discovered on Display"]. insidetoronto.com. May 6, 2010.</ref><ref name="moskovitch">Moskvitch, Katia. [https://www.bbc.co.uk/news/science-environment-11734616 "Eggs with the Oldest Known Embryos of a Dinosaur Found"]. BBC News. November 12, 2010.</ref>
+bbc.co.uk/news/science-environment-11734616 "Eggs with the Oldest Known Embryos of a Dinosaur Found"]. BBC News. November 12, 2010.</ref>
==History==
{{Main|Timeline of egg fossil research}}
-[[File:Citipati embryo.jpg|thumb|A ''[[Citipati (dinosaur)|Citipati]] osmolskae'' egg with preserved embryo, at the [[American Museum of Natural History|AMNH]].]]
-In 1859, the first scientifically documented dinosaur egg fossils were discovered in southern France by a [[Catholic priest]] and amateur naturalist named Father [[Jean-Jacques Pouech]]; he thought, however, that they were laid by giant birds.<ref name="enbd-first-5">"First Discoveries," Carpenter (1999); page 5.</ref> The first scientifically recognized dinosaur egg fossils were discovered [[serendipitously]] in 1923 by an [[American Museum of Natural History]] crew while looking for evidence of [[early humans]] in Mongolia.<ref name="enbd-first-4">"First Discoveries," Carpenter (1999); page 4.</ref> These eggs were mistakenly attributed to the locally abundant herbivore ''[[Protoceratops]]'', but are now known to be ''[[Oviraptor]]'' eggs. Egg discoveries continued to mount all over the world, leading to the development of multiple competing classification schemes.
+[[File:Citipati embryo.jpg|thumb|A ''[[Citipati (dinosaur)|Citipati]] osmolskae'' egg with preserved embryo, at the [[American Museum of Natural History|AMNH]].]]sngfjkfrjgfrffgfhrlibgfkdjrgtiufkjdgijfkrgtijbutibuer (1999); page 4.</ref> These eggs were mistakenly attributed to the locally abundant herbivore ''[[Protoceratops]]'', but are now known to be ''[[Oviraptor]]'' eggs. Egg discoveries continued to mount all over the world, leading to the development of multiple competing classification schemes.
==Identification==
' |
New page size (new_size) | 51460 |
Old page size (old_size) | 53467 |
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0 => 'bbc.co.uk/news/science-environment-11734616 "Eggs with the Oldest Known Embryos of a Dinosaur Found"]. BBC News. November 12, 2010.</ref>',
1 => '[[File:Citipati embryo.jpg|thumb|A ''[[Citipati (dinosaur)|Citipati]] osmolskae'' egg with preserved embryo, at the [[American Museum of Natural History|AMNH]].]]sngfjkfrjgfrffgfhrlibgfkdjrgtiufkjdgijfkrgtijbutibuer (1999); page 4.</ref> These eggs were mistakenly attributed to the locally abundant herbivore ''[[Protoceratops]]'', but are now known to be ''[[Oviraptor]]'' eggs. Egg discoveries continued to mount all over the world, leading to the development of multiple competing classification schemes.'
] |
Lines removed in edit (removed_lines) | [
0 => '',
1 => ''''Dinosaur eggs''' are the organic vessels in which a [[dinosaurs|dinosaur]] embryo develops. When the first scientifically documented remains of non-avian dinosaurs were being described in [[England]] during the 1820s, it was presumed that dinosaurs had laid [[egg (biology)|eggs]] because they were [[reptiles]].<ref name="enbd-first-1" /> In 1859, the first scientifically documented dinosaur egg fossils were discovered in [[France]] by Jean-Jacques Poech, although they were mistaken for giant [[bird eggs]] ([[birds]] were not yet recognized as dinosaurs at the time).',
2 => '',
3 => 'The first scientifically recognized non-avian dinosaur egg fossils were discovered in 1923 by an [[American Museum of Natural History]] crew in [[Mongolia]]. Dinosaur eggshell can be studied in [[thin section]] and viewed under a [[microscope]]. The interior of a dinosaur egg can be studied using [[CAT scans]] or by gradually dissolving away the shell with [[acid]]. Sometimes the egg preserves the remains of the developing [[embryo]] inside. The oldest known dinosaur eggs and embryos are from ''[[Massospondylus]]'', which lived during the [[Early Jurassic]], about 190 million years ago.<ref name="skinner">Skinner, Justin.[http://www.insidetoronto.com/news/local/article/812684--rom-puts-oldest-dinosaur-eggs-ever-discovered-on-display "ROM Puts Oldest Dinosaur Eggs Ever Discovered on Display"]. insidetoronto.com. May 6, 2010.</ref><ref name="moskovitch">Moskvitch, Katia. [https://www.bbc.co.uk/news/science-environment-11734616 "Eggs with the Oldest Known Embryos of a Dinosaur Found"]. BBC News. November 12, 2010.</ref>',
4 => '[[File:Citipati embryo.jpg|thumb|A ''[[Citipati (dinosaur)|Citipati]] osmolskae'' egg with preserved embryo, at the [[American Museum of Natural History|AMNH]].]]',
5 => 'In 1859, the first scientifically documented dinosaur egg fossils were discovered in southern France by a [[Catholic priest]] and amateur naturalist named Father [[Jean-Jacques Pouech]]; he thought, however, that they were laid by giant birds.<ref name="enbd-first-5">"First Discoveries," Carpenter (1999); page 5.</ref> The first scientifically recognized dinosaur egg fossils were discovered [[serendipitously]] in 1923 by an [[American Museum of Natural History]] crew while looking for evidence of [[early humans]] in Mongolia.<ref name="enbd-first-4">"First Discoveries," Carpenter (1999); page 4.</ref> These eggs were mistakenly attributed to the locally abundant herbivore ''[[Protoceratops]]'', but are now known to be ''[[Oviraptor]]'' eggs. Egg discoveries continued to mount all over the world, leading to the development of multiple competing classification schemes.'
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Parsed HTML source of the new revision (new_html) | '<div class="mw-parser-output"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Vessel for dinosaur embryo development</div>
<p class="mw-empty-elt">
</p>
<div class="thumb tright"><div class="thumbinner" style="width:162px;"><a href="/enwiki/wiki/File:Indroda_eggs.JPG" class="image"><img alt="" src="/upwiki/wikipedia/commons/thumb/9/91/Indroda_eggs.JPG/160px-Indroda_eggs.JPG" decoding="async" width="160" height="239" class="thumbimage" srcset="/upwiki/wikipedia/commons/thumb/9/91/Indroda_eggs.JPG/240px-Indroda_eggs.JPG 1.5x, /upwiki/wikipedia/commons/thumb/9/91/Indroda_eggs.JPG/320px-Indroda_eggs.JPG 2x" data-file-width="1071" data-file-height="1600" /></a> <div class="thumbcaption"><div class="magnify"><a href="/enwiki/wiki/File:Indroda_eggs.JPG" class="internal" title="Enlarge"></a></div>Fossilized <a href="/enwiki/wiki/Sauropod" class="mw-redirect" title="Sauropod">sauropod</a> eggs displayed at <a href="/enwiki/wiki/Indroda_Dinosaur_and_Fossil_Park" title="Indroda Dinosaur and Fossil Park">Indroda Dinosaur and Fossil Park</a></div></div></div>
<p>bbc.co.uk/news/science-environment-11734616 "Eggs with the Oldest Known Embryos of a Dinosaur Found"]. BBC News. November 12, 2010.</ref>
</p>
<div id="toc" class="toc" role="navigation" aria-labelledby="mw-toc-heading"><input type="checkbox" role="button" id="toctogglecheckbox" class="toctogglecheckbox" style="display:none" /><div class="toctitle" lang="en" dir="ltr"><h2 id="mw-toc-heading">Contents</h2><span class="toctogglespan"><label class="toctogglelabel" for="toctogglecheckbox"></label></span></div>
<ul>
<li class="toclevel-1 tocsection-1"><a href="#History"><span class="tocnumber">1</span> <span class="toctext">History</span></a></li>
<li class="toclevel-1 tocsection-2"><a href="#Identification"><span class="tocnumber">2</span> <span class="toctext">Identification</span></a>
<ul>
<li class="toclevel-2 tocsection-3"><a href="#False_eggs"><span class="tocnumber">2.1</span> <span class="toctext">False eggs</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-4"><a href="#Structure"><span class="tocnumber">3</span> <span class="toctext">Structure</span></a>
<ul>
<li class="toclevel-2 tocsection-5"><a href="#Layers"><span class="tocnumber">3.1</span> <span class="toctext">Layers</span></a></li>
<li class="toclevel-2 tocsection-6"><a href="#Pore_canals"><span class="tocnumber">3.2</span> <span class="toctext">Pore canals</span></a></li>
<li class="toclevel-2 tocsection-7"><a href="#Ornamentation"><span class="tocnumber">3.3</span> <span class="toctext">Ornamentation</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-8"><a href="#Classification"><span class="tocnumber">4</span> <span class="toctext">Classification</span></a>
<ul>
<li class="toclevel-2 tocsection-9"><a href="#Oogenera"><span class="tocnumber">4.1</span> <span class="toctext">Oogenera</span></a></li>
<li class="toclevel-2 tocsection-10"><a href="#Embryos"><span class="tocnumber">4.2</span> <span class="toctext">Embryos</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-11"><a href="#Taphonomy"><span class="tocnumber">5</span> <span class="toctext">Taphonomy</span></a>
<ul>
<li class="toclevel-2 tocsection-12"><a href="#Depositional_environments"><span class="tocnumber">5.1</span> <span class="toctext">Depositional environments</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-13"><a href="#Excavation_and_preparation"><span class="tocnumber">6</span> <span class="toctext">Excavation and preparation</span></a></li>
<li class="toclevel-1 tocsection-14"><a href="#Research_techniques"><span class="tocnumber">7</span> <span class="toctext">Research techniques</span></a>
<ul>
<li class="toclevel-2 tocsection-15"><a href="#Acid_dissolution"><span class="tocnumber">7.1</span> <span class="toctext">Acid dissolution</span></a></li>
<li class="toclevel-2 tocsection-16"><a href="#CAT_scans"><span class="tocnumber">7.2</span> <span class="toctext">CAT scans</span></a></li>
<li class="toclevel-2 tocsection-17"><a href="#Cathodoluminescence"><span class="tocnumber">7.3</span> <span class="toctext">Cathodoluminescence</span></a></li>
<li class="toclevel-2 tocsection-18"><a href="#Gel_electrophoresis"><span class="tocnumber">7.4</span> <span class="toctext">Gel electrophoresis</span></a></li>
<li class="toclevel-2 tocsection-19"><a href="#Geneva_lens_measure"><span class="tocnumber">7.5</span> <span class="toctext">Geneva lens measure</span></a></li>
<li class="toclevel-2 tocsection-20"><a href="#Light_microscopy"><span class="tocnumber">7.6</span> <span class="toctext">Light microscopy</span></a></li>
<li class="toclevel-2 tocsection-21"><a href="#Scanning_electron_microscopy"><span class="tocnumber">7.7</span> <span class="toctext">Scanning electron microscopy</span></a></li>
<li class="toclevel-2 tocsection-22"><a href="#Mass_spectrometry"><span class="tocnumber">7.8</span> <span class="toctext">Mass spectrometry</span></a></li>
<li class="toclevel-2 tocsection-23"><a href="#X_rays"><span class="tocnumber">7.9</span> <span class="toctext">X rays</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-24"><a href="#Footnotes"><span class="tocnumber">8</span> <span class="toctext">Footnotes</span></a></li>
<li class="toclevel-1 tocsection-25"><a href="#References"><span class="tocnumber">9</span> <span class="toctext">References</span></a></li>
<li class="toclevel-1 tocsection-26"><a href="#External_links"><span class="tocnumber">10</span> <span class="toctext">External links</span></a></li>
</ul>
</div>
<h2><span class="mw-headline" id="History">History</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=1" title="Edit section: History">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<style data-mw-deduplicate="TemplateStyles:r1033289096">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/enwiki/wiki/Timeline_of_egg_fossil_research" title="Timeline of egg fossil research">Timeline of egg fossil research</a></div>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/enwiki/wiki/File:Citipati_embryo.jpg" class="image"><img alt="" src="/upwiki/wikipedia/commons/thumb/9/96/Citipati_embryo.jpg/220px-Citipati_embryo.jpg" decoding="async" width="220" height="120" class="thumbimage" srcset="/upwiki/wikipedia/commons/thumb/9/96/Citipati_embryo.jpg/330px-Citipati_embryo.jpg 1.5x, /upwiki/wikipedia/commons/thumb/9/96/Citipati_embryo.jpg/440px-Citipati_embryo.jpg 2x" data-file-width="1004" data-file-height="546" /></a> <div class="thumbcaption"><div class="magnify"><a href="/enwiki/wiki/File:Citipati_embryo.jpg" class="internal" title="Enlarge"></a></div>A <i><a href="/enwiki/wiki/Citipati_(dinosaur)" class="mw-redirect" title="Citipati (dinosaur)">Citipati</a> osmolskae</i> egg with preserved embryo, at the <a href="/enwiki/wiki/American_Museum_of_Natural_History" title="American Museum of Natural History">AMNH</a>.</div></div></div><p>sngfjkfrjgfrffgfhrlibgfkdjrgtiufkjdgijfkrgtijbutibuer (1999); page 4.</ref> These eggs were mistakenly attributed to the locally abundant herbivore <i><a href="/enwiki/wiki/Protoceratops" title="Protoceratops">Protoceratops</a></i>, but are now known to be <i><a href="/enwiki/wiki/Oviraptor" title="Oviraptor">Oviraptor</a></i> eggs. Egg discoveries continued to mount all over the world, leading to the development of multiple competing classification schemes.
</p><h2><span class="mw-headline" id="Identification">Identification</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=2" title="Edit section: Identification">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<p>Fossil dinosaur eggshell fragments can be recognized based on three important traits. Their thickness should be roughly uniform, they are usually slightly curved, and their surface is covered in tiny pores. Less frequently, the <a href="https://en.wiktionary.org/wiki/concave" class="extiw" title="wikt:concave">concave</a> underside of the eggshell fragment will preserve bumps known as <a href="/enwiki/wiki/Mammillae" class="mw-redirect" title="Mammillae">mammillae</a>. Sometimes the embryo had absorbed so much of the calcium that the mammilae need a magnifying glass or <a href="/enwiki/wiki/Microscope" title="Microscope">microscope</a> to be seen.<sup id="cite_ref-enbd-collecting-115_1-0" class="reference"><a href="#cite_note-enbd-collecting-115-1">[1]</a></sup> However, there are many kinds of naturally occurring objects which can resemble fossil eggs. These can fool even professional paleontologists.<sup id="cite_ref-enbd-fake-118_2-0" class="reference"><a href="#cite_note-enbd-fake-118-2">[2]</a></sup>
</p>
<div class="thumb tleft"><div class="thumbinner" style="width:222px;"><a href="/enwiki/wiki/File:Zkamen%C4%9Bl%C3%A9_vejce_dinosaura_z_pou%C5%A1t%C4%9B_Gobi,_expozice_N%C3%A1rodn%C3%ADho_muzea_v_Praze_(2007).jpg" class="image"><img alt="" src="/upwiki/wikipedia/commons/thumb/a/a5/Zkamen%C4%9Bl%C3%A9_vejce_dinosaura_z_pou%C5%A1t%C4%9B_Gobi%2C_expozice_N%C3%A1rodn%C3%ADho_muzea_v_Praze_%282007%29.jpg/220px-Zkamen%C4%9Bl%C3%A9_vejce_dinosaura_z_pou%C5%A1t%C4%9B_Gobi%2C_expozice_N%C3%A1rodn%C3%ADho_muzea_v_Praze_%282007%29.jpg" decoding="async" width="220" height="165" class="thumbimage" srcset="/upwiki/wikipedia/commons/thumb/a/a5/Zkamen%C4%9Bl%C3%A9_vejce_dinosaura_z_pou%C5%A1t%C4%9B_Gobi%2C_expozice_N%C3%A1rodn%C3%ADho_muzea_v_Praze_%282007%29.jpg/330px-Zkamen%C4%9Bl%C3%A9_vejce_dinosaura_z_pou%C5%A1t%C4%9B_Gobi%2C_expozice_N%C3%A1rodn%C3%ADho_muzea_v_Praze_%282007%29.jpg 1.5x, /upwiki/wikipedia/commons/thumb/a/a5/Zkamen%C4%9Bl%C3%A9_vejce_dinosaura_z_pou%C5%A1t%C4%9B_Gobi%2C_expozice_N%C3%A1rodn%C3%ADho_muzea_v_Praze_%282007%29.jpg/440px-Zkamen%C4%9Bl%C3%A9_vejce_dinosaura_z_pou%C5%A1t%C4%9B_Gobi%2C_expozice_N%C3%A1rodn%C3%ADho_muzea_v_Praze_%282007%29.jpg 2x" data-file-width="2560" data-file-height="1920" /></a> <div class="thumbcaption"><div class="magnify"><a href="/enwiki/wiki/File:Zkamen%C4%9Bl%C3%A9_vejce_dinosaura_z_pou%C5%A1t%C4%9B_Gobi,_expozice_N%C3%A1rodn%C3%ADho_muzea_v_Praze_(2007).jpg" class="internal" title="Enlarge"></a></div>Fossilized dinosaur egg from the Gobi desert, National Museum in Prague</div></div></div>
<h3><span class="mw-headline" id="False_eggs">False eggs</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=3" title="Edit section: False eggs">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p><b>Calculus:</b> Calculi are egg-like objects formed in the stomachs of <a href="/enwiki/wiki/Ruminants" class="mw-redirect" title="Ruminants">ruminants</a> such as <a href="/enwiki/wiki/Cattle" title="Cattle">cattle</a>, <a href="/enwiki/wiki/Deer" title="Deer">deer</a>, <a href="/enwiki/wiki/Elk" title="Elk">elk</a>, and <a href="/enwiki/wiki/Goats" class="mw-redirect" title="Goats">goats</a>. Calculus formation is a defense mechanism protecting the ruminant's stomach from damage if it swallows a foreign object while grazing. After ingestion, the object is covered by the same material composing bone, <a href="/enwiki/wiki/Calcium_phosphate" title="Calcium phosphate">calcium phosphate</a>, and eventually vomited out of the animal's system. These "stomach stones" tend to range in size from 1 to 6 centimeters. Larger sizes are known but very rare.<sup id="cite_ref-enbd-fake-121_3-0" class="reference"><a href="#cite_note-enbd-fake-121-3">[3]</a></sup> Sometimes tiny dimples cover the surface of a stomach stone, which can fool observers into thinking they are the pores of an egg.<sup id="cite_ref-enbd-fake-120_4-0" class="reference"><a href="#cite_note-enbd-fake-120-4">[4]</a></sup> Fossil egg expert Ken Carpenter has described stomach stones as the most egg-like natural objects, noting that they are "the trickiest [egg-like] objects to correctly identify".<sup id="cite_ref-enbd-fake-120-121_5-0" class="reference"><a href="#cite_note-enbd-fake-120-121-5">[5]</a></sup> Calculi are so egg-like that on one occasion a detailed description of a stomach stone misidentified as a fossil egg was published in the scientific literature.<sup id="cite_ref-enbd-fake-120_4-1" class="reference"><a href="#cite_note-enbd-fake-120-4">[4]</a></sup> Calculi can be distinguished from real egg fossils because when they are broken open, they show the layers of calcium phosphate and the foreign object at the core.<sup id="cite_ref-enbd-fake-120_4-2" class="reference"><a href="#cite_note-enbd-fake-120-4">[4]</a></sup> Multiple layers of eggshell are known in <a href="/enwiki/wiki/Egg_paleopathology" title="Egg paleopathology">pathological eggs</a>, but these layers don't go all the way down to its core the way a stomach stone's do. Calculi are often suspiciously intact, unlike fossil eggs, which are usually damaged.<sup id="cite_ref-enbd-fake-121_3-1" class="reference"><a href="#cite_note-enbd-fake-121-3">[3]</a></sup> Stomach stones also lack distinct shells with their attending structural components like continuous or prismatic layers, mammillae, and pores.<sup id="cite_ref-enbd-fake-120_4-3" class="reference"><a href="#cite_note-enbd-fake-120-4">[4]</a></sup>
</p><p><b>Concretions:</b> <a href="/enwiki/wiki/Concretions" class="mw-redirect" title="Concretions">Concretions</a> are formed when decaying organisms change the chemistry of their immediate surroundings in a manner that is conducive to minerals <a href="/enwiki/wiki/Precipitating" class="mw-redirect" title="Precipitating">precipitating</a> out of solution. These minerals accumulate in a mass roughly shaped like the region of altered chemistry. Sometimes the mass produced is egg-shaped.<sup id="cite_ref-enbd-fake-119_6-0" class="reference"><a href="#cite_note-enbd-fake-119-6">[6]</a></sup> Most egg-shaped concretions have uniform interiors, however some form through the accumulation of mineral in layers.<sup id="cite_ref-enbd-fake-119-120_7-0" class="reference"><a href="#cite_note-enbd-fake-119-120-7">[7]</a></sup> These layered concretions can be even harder to recognize than those with uniform interiors because the layers can resemble egg white and yolk. The yellow of the false yolk comes from minerals like limonite, siderite, and sulfur.<sup id="cite_ref-enbd-fake-120_4-4" class="reference"><a href="#cite_note-enbd-fake-120-4">[4]</a></sup>
</p><p>Concretions also generally lack distinct shells, although sometimes they can appear to have them if their outside surfaces have been case-hardened. Since their interiors are softer, erosion can separate the two, creating eggshell pseudofossils. Real egg fossils should preserve eggshell structures like pores, mammillae, and prismatic or continuous layers, which are not present in concretions. Any given concretion is unlikely to be exactly the same size as any other, so associations of egg-like objects of different sizes are probably not real eggs at all. Concretions can also be far larger than any real egg so an apparently unnaturally large "egg" has probably been misidentified.<sup id="cite_ref-enbd-fake-120_4-5" class="reference"><a href="#cite_note-enbd-fake-120-4">[4]</a></sup>
</p><p><b>Insect trace fossils:</b> Sometimes the living or breeding chambers of an insect burrow are so perfectly egg-shaped that even a paleontologist can mistake a natural cast of these chambers for a fossil egg. Insect burrow fossils can sometimes be distinguished from real egg fossils by the presence of "scratch marks" on their surface left by the insect during the burrow's original excavation. Fossil insect pupae can also resemble eggs. After death and burial, the decomposition of a deceased pupa would leave a gap in the sediment that could be filled with minerals carried by groundwater, forming an egg-like cast. These pseudo-eggs can be recognized by their small size (usually not much longer than a centimeter or two) and lack of an eggshell with its typical anatomy.<sup id="cite_ref-enbd-fake-120_4-6" class="reference"><a href="#cite_note-enbd-fake-120-4">[4]</a></sup>
</p><p><b>Stones:</b> The erosive effects of water can sometimes round rocks into egg-like shapes.<sup id="cite_ref-enbd-fake-119_6-1" class="reference"><a href="#cite_note-enbd-fake-119-6">[6]</a></sup>
</p>
<h2><span class="mw-headline" id="Structure">Structure</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=4" title="Edit section: Structure">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<p>Paleontologists' knowledge of the structure of dinosaur eggs is limited to the hard shell. However, it can be inferred that dinosaur eggs had an <a href="/enwiki/wiki/Amnion" title="Amnion">amnion</a>, <a href="/enwiki/wiki/Chorion_(egg)" class="mw-redirect" title="Chorion (egg)">chorion</a>, and an <a href="/enwiki/wiki/Allantois" title="Allantois">allantois</a>, the three major membranes in modern bird and reptile eggs. Dinosaur eggs vary greatly in size and shape, but even the largest dinosaur eggs (<i><a href="/enwiki/wiki/Megaloolithus" title="Megaloolithus">Megaloolithus</a></i>) are smaller than the largest known bird eggs, which were laid by the extinct <a href="/enwiki/wiki/Elephant_bird" title="Elephant bird">elephant bird</a>. Dinosaur eggs range in shape from spherical to highly elongated (some specimens three times longer than they are wide). Some elongated eggs are symmetrical, whereas others have one rounded end and one pointed end (similar to bird eggs). Most elongated eggs were laid by theropods and have an avian-like eggshell, whereas the spherical eggs typically represent non-theropod dinosaurs.<sup id="cite_ref-Making_an_Egg_8-0" class="reference"><a href="#cite_note-Making_an_Egg-8">[8]</a></sup>
</p>
<div class="thumb tright"><div class="thumbinner" style="width:242px;"><a href="/enwiki/wiki/File:Eggshell_Structure_diagram.jpg" class="image"><img alt="" src="/upwiki/wikipedia/commons/thumb/6/62/Eggshell_Structure_diagram.jpg/240px-Eggshell_Structure_diagram.jpg" decoding="async" width="240" height="115" class="thumbimage" srcset="/upwiki/wikipedia/commons/thumb/6/62/Eggshell_Structure_diagram.jpg/360px-Eggshell_Structure_diagram.jpg 1.5x, /upwiki/wikipedia/commons/thumb/6/62/Eggshell_Structure_diagram.jpg/480px-Eggshell_Structure_diagram.jpg 2x" data-file-width="593" data-file-height="283" /></a> <div class="thumbcaption"><div class="magnify"><a href="/enwiki/wiki/File:Eggshell_Structure_diagram.jpg" class="internal" title="Enlarge"></a></div>Diagram of a two-layered eggshell.</div></div></div><p> Fossil dinosaur eggshells, like modern bird and reptile eggshells, are made up of <a href="/enwiki/wiki/Calcium_carbonate" title="Calcium carbonate">calcium carbonate</a> crystal units. The basic arrangement and structure of these eggshell units (called the ultrastructure) is used to divide fossil eggs into several basic types, including the spherulitic, prismatic, and ornithoid basic types, which contain dinosaurs.<sup id="cite_ref-How_to_Study_9-0" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup> Dinosaur eggs further <a href="#Classification">classified</a> by the microstructural aspects of the crystalline structure of the eggshell units and by the type of their pores and their shell ornamentation.<sup id="cite_ref-UCMP_10-0" class="reference"><a href="#cite_note-UCMP-10">[10]</a></sup>
</p><h3><span class="mw-headline" id="Layers">Layers</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=5" title="Edit section: Layers">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p>Dinosaur eggshells are divided into one, two, or three layers of distinct ultrastructure.<sup id="cite_ref-UCMP_10-1" class="reference"><a href="#cite_note-UCMP-10">[10]</a></sup><sup id="cite_ref-11" class="reference"><a href="#cite_note-11">[11]</a></sup><sup id="cite_ref-12" class="reference"><a href="#cite_note-12">[12]</a></sup><sup id="cite_ref-13" class="reference"><a href="#cite_note-13">[13]</a></sup>
</p><p>The innermost layer, known as the mammillary layer or the cone layer, is only found in theropod eggs (the prismatic and ornithoid basic types). It is composed of cone-shaped structures called mammillae at the base of each shell unit. Mammillae are the first part of the eggshell to form. Each mammilla forms from crystals radiating outward from an organic core until they touch neighboring mammillae and grow upwards into the next layer.<sup id="cite_ref-Making_an_Egg_8-1" class="reference"><a href="#cite_note-Making_an_Egg-8">[8]</a></sup><sup id="cite_ref-UCMP_10-2" class="reference"><a href="#cite_note-UCMP-10">[10]</a></sup> In spherulitic eggs, the eggs of non-theropod dinosaurs, the eggshell units grow upward from their organic cores; the base of each eggshell unit is rounded, but is not a true mammilla because it does not have a distinct ultrastructure from the top of the unit.<sup id="cite_ref-Making_an_Egg_8-2" class="reference"><a href="#cite_note-Making_an_Egg-8">[8]</a></sup><sup id="cite_ref-How_to_Study_9-1" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup>
</p><p>The second layer is alternately called the prismatic layer, the columnar layer, the continuous layer, the crystalline layer,<sup id="cite_ref-Making_an_Egg_8-3" class="reference"><a href="#cite_note-Making_an_Egg-8">[8]</a></sup> the cryptoprismatic layer,<sup id="cite_ref-Simon_2014_14-0" class="reference"><a href="#cite_note-Simon_2014-14">[14]</a></sup> the palisade layer,<sup id="cite_ref-UCMP_10-3" class="reference"><a href="#cite_note-UCMP-10">[10]</a></sup> the spongy layer,<sup id="cite_ref-M1996_15-0" class="reference"><a href="#cite_note-M1996-15">[15]</a></sup> or the single layer.<sup id="cite_ref-Vianey-Liaud_and_Lopez-Martinez_1997_16-0" class="reference"><a href="#cite_note-Vianey-Liaud_and_Lopez-Martinez_1997-16">[16]</a></sup> In this layer, the shell units can be distinct, partially fused together, or entirely continuous.<sup id="cite_ref-How_to_Study_9-2" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup> In some dinosaur eggs, the prismatic layer exhibits squamatic ultrastructure, where the prismatic structure is obscured by a rough texture resembling lizard skin.<sup id="cite_ref-UCMP_10-4" class="reference"><a href="#cite_note-UCMP-10">[10]</a></sup><sup id="cite_ref-How_to_Study_9-3" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup>
</p><p>Though rare in non-avian dinosaurs, some theropod eggs and most bird eggs have a third layer (known as the external layer) made up of vertical calcite crystals.<sup id="cite_ref-UCMP_10-5" class="reference"><a href="#cite_note-UCMP-10">[10]</a></sup><sup id="cite_ref-Making_an_Egg_8-4" class="reference"><a href="#cite_note-Making_an_Egg-8">[8]</a></sup>
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<h3><span class="mw-headline" id="Pore_canals">Pore canals</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=6" title="Edit section: Pore canals">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p>In all eggs, the embryo must breathe. In egg-laying amniotes (including dinosaurs), pore canals cutting through the eggshell allow gas exchange between the embryo and the outside world. Dinosaur eggshells exhibit a lot of diversity in pore size, density, and shape. One early attempt at classification of dinosaurian eggs, proposed by the Soviet paleontologist A. Sochava, was based on grouping eggs by their pore systems.<sup id="cite_ref-Intro_17-0" class="reference"><a href="#cite_note-Intro-17">[17]</a></sup> This system was abandoned when it was discovered that different eggs could have very similar pores, but pore systems do play an important role in modern eggshell parataxonomy.<sup id="cite_ref-How_to_Study_9-4" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup> The density and width of the pores, combined with the eggshell's thickness can be used to predict the <a href="/enwiki/w/index.php?title=Gas_conductance&action=edit&redlink=1" class="new" title="Gas conductance (page does not exist)">gas conductance</a> of a dinosaur's egg.<sup id="cite_ref-UCMP_10-6" class="reference"><a href="#cite_note-UCMP-10">[10]</a></sup> This can provide both information about nesting behavior and about the climate: eggs buried in sediment have higher rates of gas conductance than those laid in the open, and eggs laid in arid environments have lower gas conductance (to prevent water loss) than those laid in more humid conditions.<sup id="cite_ref-UCMPV_18-0" class="reference"><a href="#cite_note-UCMPV-18">[18]</a></sup>
</p><p>Paleontologist and fossil egg expert Kenneth Carpenter catalogued six types of pore systems:<sup id="cite_ref-How_to_Study_9-5" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup>
</p>
<ol><li>Angusticanaliculate - Long, narrow, straight pores with low pore density. These eggs would have a low gas exchange rate, and therefore they were typically laid in dry areas.<sup id="cite_ref-How_to_Study_9-6" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup></li>
<li>Tubocanaliculate - Large diameter pores with funnel-shaped openings on both inner and outer surfaces of the shell. These eggs would have a high gas exchange rate, and therefore were probably buried in humid mounds.<sup id="cite_ref-How_to_Study_9-7" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup></li>
<li>Multicanaliculate - Numerous large, branching, and closely spaced pore canals. They have a high gas exchange rate, so like tubocanaliculate eggs they were probably also buried humid mounds.<sup id="cite_ref-How_to_Study_9-8" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup></li>
<li>Prolatocanaliculate - Pores vary in width throughout their length. Gas exchange water loss rates are variable, so these eggs could have been laid in many different environments. This type is subdivided into foveocanaliculate with larger pore openings, and lagenocanaliculate with narrower pore openings.<sup id="cite_ref-How_to_Study_9-9" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup></li>
<li>Rimocanaliculate - Very narrow slitlike pore canals. This pore system is seen in modern ostriches, so these eggs were laid in open nests, similar to how ostriches do today.<sup id="cite_ref-How_to_Study_9-10" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup></li>
<li>Obliquicanaliculate - These canals cut diagonally through multiple eggshell units instead of going between them like in other pore systems. Obliquicanaliculate pores are only found in a single oogenus: <i><a href="/enwiki/wiki/Preprismatoolithus" title="Preprismatoolithus">Preprismatoolithus</a></i>.<sup id="cite_ref-How_to_Study_9-11" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup></li></ol>
<h3><span class="mw-headline" id="Ornamentation">Ornamentation</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=7" title="Edit section: Ornamentation">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p>Unlike most modern eggs, many dinosaur eggs had a rough texture formed by nodes and ridges ornamenting the surface of their shell.<sup id="cite_ref-UCMP_10-7" class="reference"><a href="#cite_note-UCMP-10">[10]</a></sup> This is predominant in Cretaceous dinosaur eggs, but very rare in eggs from the Jurassic or Triassic.<sup id="cite_ref-Nests_19-0" class="reference"><a href="#cite_note-Nests-19">[19]</a></sup> Because of the lack of modern analogues, the purpose of eggshell ornamentation is unknown,<sup id="cite_ref-UCMP_10-8" class="reference"><a href="#cite_note-UCMP-10">[10]</a></sup> but many functions have been proposed.<sup id="cite_ref-Nests_19-1" class="reference"><a href="#cite_note-Nests-19">[19]</a></sup> Possibly, they provided extra strength to the eggshell without having pore canals too long for adequate gas exchange. They could also have helped keep substrate away from the pore openings of eggs that were buried, but modern <a href="/enwiki/wiki/Turtle" title="Turtle">turtles</a> and <a href="/enwiki/wiki/Crocodylian" class="mw-redirect" title="Crocodylian">crocodylians</a> which bury their eggs have smooth eggshells, so this adaptation is not necessary for animals which bury their eggs. Another hypothesis, proposed by R. M. Mellon in <a href="/enwiki/wiki/1982_in_paleontology" title="1982 in paleontology">1982</a> in his <a href="/enwiki/wiki/Senior_thesis" class="mw-redirect" title="Senior thesis">senior thesis</a> at <a href="/enwiki/wiki/Princeton_University" title="Princeton University">Princeton University</a>, is that the ridges and nodes would have formed pathways for gas to flow across the surface of the eggshell, preventing accumulation of too much <a href="/enwiki/wiki/Carbon_dioxide" title="Carbon dioxide">CO<sub>2</sub></a> and aiding the flow of oxygen and water vapor.<sup id="cite_ref-Nests_19-2" class="reference"><a href="#cite_note-Nests-19">[19]</a></sup>
</p><p>Since it varies from egg to egg, the texture of an eggshell's ornamentation is useful for classification. Six types of ornamentation were catalogued by Carpenter in 1999:<sup id="cite_ref-How_to_Study_9-12" class="reference"><a href="#cite_note-How_to_Study-9">[9]</a></sup>
</p>
<ol><li>Compactituberculate - The dome-shaped tops of the shell units form a dense covering of nodes on the surface of the eggshell. This type of ornamentation is most commonly seen in <a href="/enwiki/wiki/Megaloolithidae" title="Megaloolithidae">megaloolithids</a>.<sup id="cite_ref-Soto_20-0" class="reference"><a href="#cite_note-Soto-20">[20]</a></sup></li>
<li>Sagenotuberculate - The nodes and ridges form a netlike pattern interspersed with pits and grooves.</li>
<li>Dispersituberculate - Scattered nodes. This ornamentation is seen on the poles of elongated eggs, which may have allowed accumulations CO<sub>2</sub> at the poles to escape between the nodes.<sup id="cite_ref-Nests_19-3" class="reference"><a href="#cite_note-Nests-19">[19]</a></sup></li>
<li>Lineartuberculate - Ridges, and chains of ridges and nodes form lines parallel to the long axis of the egg.</li>
<li>Ramotuberculate - Irregular chains of nodes, typically found as a transition between the lineartuberculate midsection and dispersituberculate ends of elongated eggs.</li>
<li>Anastomotuberculate - Ridges similar to lineartuberculate, but instead form wavy, branching, or <a href="/enwiki/wiki/Anastomosing" class="mw-redirect" title="Anastomosing">anastomosing</a> patterns resembling the water ripple marks in sand.</li></ol>
<h2><span class="mw-headline" id="Classification">Classification</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=8" title="Edit section: Classification">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<p>The classification of dinosaur eggs is based on the structure of the egg shells viewed in thin section via microscope, although new techniques such as electron backscatter diffraction have been used.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21">[21]</a></sup> There are three main categories of dinosaur eggs: spherulitic (sauropods and <a href="/enwiki/wiki/Hadrosaurid" class="mw-redirect" title="Hadrosaurid">hadrosaurs</a>),<sup id="cite_ref-basic-spherulitic-136-137_22-0" class="reference"><a href="#cite_note-basic-spherulitic-136-137-22">[22]</a></sup> <a href="/enwiki/wiki/Prism_(geometry)" title="Prism (geometry)">prismatic</a>,<sup id="cite_ref-basic-prismatic-137_23-0" class="reference"><a href="#cite_note-basic-prismatic-137-23">[23]</a></sup> and ornithoid (<a href="/enwiki/wiki/Theropoda" title="Theropoda">theropods</a>, including modern birds).<sup id="cite_ref-ubristol_24-0" class="reference"><a href="#cite_note-ubristol-24">[24]</a></sup>
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<h3><span class="mw-headline" id="Oogenera">Oogenera</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=9" title="Edit section: Oogenera">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p><a href="/enwiki/wiki/Oogenus" class="mw-redirect" title="Oogenus">Oogenera</a> are taxonomic names for types of eggshell. Nearly three dozen oogenera have been named for dinosaur eggs:
</p>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/enwiki/wiki/File:Segnosaurus_nest_2.jpg" class="image"><img alt="" src="/upwiki/wikipedia/commons/thumb/a/a4/Segnosaurus_nest_2.jpg/220px-Segnosaurus_nest_2.jpg" decoding="async" width="220" height="147" class="thumbimage" srcset="/upwiki/wikipedia/commons/thumb/a/a4/Segnosaurus_nest_2.jpg/330px-Segnosaurus_nest_2.jpg 1.5x, /upwiki/wikipedia/commons/thumb/a/a4/Segnosaurus_nest_2.jpg/440px-Segnosaurus_nest_2.jpg 2x" data-file-width="2044" data-file-height="1367" /></a> <div class="thumbcaption"><div class="magnify"><a href="/enwiki/wiki/File:Segnosaurus_nest_2.jpg" class="internal" title="Enlarge"></a></div><a href="/enwiki/wiki/Therizinosaur" class="mw-redirect" title="Therizinosaur">Therizinosaur</a> nest and eggs (<i><a href="/enwiki/wiki/Cf." title="Cf.">cf.</a></i> <i><a href="/enwiki/wiki/Segnosaurus" title="Segnosaurus">Segnosaurus</a></i>) in from <i><a href="/enwiki/wiki/Dinosaurland" class="mw-redirect" title="Dinosaurland">Dinosaurland</a></i> in <a href="/enwiki/wiki/Lyme_Regis" title="Lyme Regis">Lyme Regis</a>, England.</div></div></div>
<style data-mw-deduplicate="TemplateStyles:r998391716">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col" style="column-width: 20em;">
<ul><li><i><a href="/enwiki/wiki/Ageroolithus" title="Ageroolithus">Ageroolithus</a></i></li>
<li><i><a href="/enwiki/wiki/Apheloolithus" title="Apheloolithus">Apheloolithus</a></i><sup id="cite_ref-DFG03_25-0" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/wiki/Boletuoolithus" class="mw-redirect" title="Boletuoolithus">Boletuoolithus</a></i><sup id="cite_ref-26" class="reference"><a href="#cite_note-26">[26]</a></sup></li>
<li><i><a href="/enwiki/wiki/Cairanoolithus" title="Cairanoolithus">Cairanoolithus</a></i><sup id="cite_ref-27" class="reference"><a href="#cite_note-27">[27]</a></sup></li>
<li><i><a href="/enwiki/wiki/Continuoolithus" title="Continuoolithus">Continuoolithus</a></i><sup id="cite_ref-DFG03_25-1" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/wiki/Dendroolithus" title="Dendroolithus">Dendroolithus</a></i><sup id="cite_ref-DFG03_25-2" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/wiki/Dictyoolithus" title="Dictyoolithus">Dictyoolithus</a></i><sup id="cite_ref-28" class="reference"><a href="#cite_note-28">[28]</a></sup></li>
<li><i><a href="/enwiki/wiki/Dispersituberoolithus" title="Dispersituberoolithus">Dispersituberoolithus</a></i></li>
<li><i><a href="/enwiki/wiki/Ellipsoolithus" title="Ellipsoolithus">Ellipsoolithus</a></i><sup id="cite_ref-29" class="reference"><a href="#cite_note-29">[29]</a></sup></li>
<li><i><a href="/enwiki/wiki/Elongatoolithus" title="Elongatoolithus">Elongatoolithus</a></i><sup id="cite_ref-30" class="reference"><a href="#cite_note-30">[30]</a></sup></li>
<li><i><a href="/enwiki/wiki/Faveoolithus" class="mw-redirect" title="Faveoolithus">Faveoolithus</a></i><sup id="cite_ref-DFG03_25-3" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/wiki/Heishanoolithus" title="Heishanoolithus">Heishanoolithus</a></i><sup id="cite_ref-31" class="reference"><a href="#cite_note-31">[31]</a></sup></li>
<li><i><a href="/enwiki/wiki/Laevisoolithus" title="Laevisoolithus">Laevisoolithus</a></i></li>
<li><i><a href="/enwiki/wiki/Macroolithus" title="Macroolithus">Macroolithus</a></i><sup id="cite_ref-32" class="reference"><a href="#cite_note-32">[32]</a></sup></li>
<li><i><a href="/enwiki/wiki/Macroelongatoolithus" title="Macroelongatoolithus">Macroelongatoolithus</a></i><sup id="cite_ref-33" class="reference"><a href="#cite_note-33">[33]</a></sup></li>
<li><i><a href="/enwiki/wiki/Megaloolithus" title="Megaloolithus">Megaloolithus</a></i><sup id="cite_ref-34" class="reference"><a href="#cite_note-34">[34]</a></sup></li>
<li><i><a href="/enwiki/wiki/Nanshiungoolithus" class="mw-redirect" title="Nanshiungoolithus">Nanshiungoolithus</a></i><sup id="cite_ref-35" class="reference"><a href="#cite_note-35">[35]</a></sup></li>
<li><i><a href="/enwiki/wiki/Oblongoolithus" title="Oblongoolithus">Oblongoolithus</a></i></li>
<li><i><a href="/enwiki/wiki/Ovaloolithus" title="Ovaloolithus">Ovaloolithus</a></i><sup id="cite_ref-36" class="reference"><a href="#cite_note-36">[36]</a></sup></li>
<li><i><a href="/enwiki/wiki/Pachycorioolithus" title="Pachycorioolithus">Pachycorioolithus</a></i><sup id="cite_ref-Lawver_et_al_2016_37-0" class="reference"><a href="#cite_note-Lawver_et_al_2016-37">[37]</a></sup></li>
<li><i><a href="/enwiki/wiki/Paraspheroolithus" class="mw-redirect" title="Paraspheroolithus">Paraspheroolithus</a></i><sup id="cite_ref-38" class="reference"><a href="#cite_note-38">[38]</a></sup></li>
<li><i><a href="/enwiki/wiki/Phaceloolithus" title="Phaceloolithus">Phaceloolithus</a></i><sup id="cite_ref-DFG03_25-4" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/w/index.php?title=Placoolithus&action=edit&redlink=1" class="new" title="Placoolithus (page does not exist)">Placoolithus</a></i><sup id="cite_ref-39" class="reference"><a href="#cite_note-39">[39]</a></sup></li>
<li><i><a href="/enwiki/wiki/Porituberoolithus" title="Porituberoolithus">Porituberoolithus</a></i></li>
<li><i><a href="/enwiki/wiki/Polyclonoolithus" title="Polyclonoolithus">Polyclonoolithus</a></i><sup id="cite_ref-Xie_et_al_2016_40-0" class="reference"><a href="#cite_note-Xie_et_al_2016-40">[40]</a></sup></li>
<li><i><a href="/enwiki/wiki/Preprismatoolithus" title="Preprismatoolithus">Preprismatoolithus</a></i><sup id="cite_ref-DFG03_25-5" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/wiki/Prismatoolithus" title="Prismatoolithus">Prismatoolithus</a></i><sup id="cite_ref-41" class="reference"><a href="#cite_note-41">[41]</a></sup></li>
<li><i><a href="/enwiki/wiki/Protoceratopsidovum" title="Protoceratopsidovum">Protoceratopsidovum</a></i><sup id="cite_ref-The_Palaeobiology_Database_42-0" class="reference"><a href="#cite_note-The_Palaeobiology_Database-42">[42]</a></sup></li>
<li><i><a href="/enwiki/wiki/Pseudogeckoolithus" title="Pseudogeckoolithus">Pseudogeckoolithus</a></i></li>
<li><i><a href="/enwiki/wiki/Shixingoolithus" title="Shixingoolithus">Shixingoolithus</a></i><sup id="cite_ref-43" class="reference"><a href="#cite_note-43">[43]</a></sup></li>
<li><i><a href="/enwiki/wiki/Sphaerovum" title="Sphaerovum">Sphaerovum</a></i><sup id="cite_ref-DFG03_25-6" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/wiki/Spheroolithus" title="Spheroolithus">Spheroolithus</a></i><sup id="cite_ref-44" class="reference"><a href="#cite_note-44">[44]</a></sup></li>
<li><i><a href="/enwiki/w/index.php?title=Spheruprismatoolithus&action=edit&redlink=1" class="new" title="Spheruprismatoolithus (page does not exist)">Spheruprismatoolithus</a></i><sup id="cite_ref-The_Palaeobiology_Database_42-1" class="reference"><a href="#cite_note-The_Palaeobiology_Database-42">[42]</a></sup></li>
<li><i><a href="/enwiki/wiki/Stromatoolithus" title="Stromatoolithus">Stromatoolithus</a></i><sup id="cite_ref-DFG03_25-7" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/wiki/Subtiliolithus" title="Subtiliolithus">Subtiliolithus</a></i><sup id="cite_ref-DFG03_25-8" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/wiki/Tacuarembovum" title="Tacuarembovum">Tacuarembovum</a></i><sup id="cite_ref-DFG03_25-9" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li>
<li><i><a href="/enwiki/wiki/Trachoolithus" title="Trachoolithus">Trachoolithus</a></i><sup id="cite_ref-45" class="reference"><a href="#cite_note-45">[45]</a></sup></li>
<li><i><a href="/enwiki/wiki/Tristraguloolithus" title="Tristraguloolithus">Tristraguloolithus</a></i></li>
<li><i><a href="/enwiki/wiki/Youngoolithus" title="Youngoolithus">Youngoolithus</a></i><sup id="cite_ref-DFG03_25-10" class="reference"><a href="#cite_note-DFG03-25">[25]</a></sup></li></ul>
</div>
<h3><span class="mw-headline" id="Embryos">Embryos</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=10" title="Edit section: Embryos">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p>Dinosaur embryos, the animal inside the eggs, are very rare but useful to understand <a href="/enwiki/wiki/Ontogeny" title="Ontogeny">ontogeny</a>, <a href="/enwiki/wiki/Heterochrony" title="Heterochrony">heterochrony</a>, and dinosaur <a href="/enwiki/wiki/Systematics" title="Systematics">systematics</a>.
Embryo fossils are known from:
</p>
<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r998391716"/><div class="div-col" style="column-width: 20em;">
<ul><li><i><a href="/enwiki/wiki/Beibeilong" title="Beibeilong">Beibeilong</a></i></li>
<li><i><a href="/enwiki/wiki/Citipati_(dinosaur)" class="mw-redirect" title="Citipati (dinosaur)">Citipati</a></i><sup id="cite_ref-46" class="reference"><a href="#cite_note-46">[46]</a></sup></li>
<li><i><a href="/enwiki/wiki/Heyuannia" title="Heyuannia">Heyuannia</a></i></li>
<li><i><a href="/enwiki/wiki/Lufengosaurus" title="Lufengosaurus">Lufengosaurus</a></i></li>
<li><i><a href="/enwiki/wiki/Lourinhanosaurus" title="Lourinhanosaurus">Lourinhanosaurus</a></i><sup id="cite_ref-mateus-et-al_47-0" class="reference"><a href="#cite_note-mateus-et-al-47">[47]</a></sup><sup id="cite_ref-dericqles-et-al_48-0" class="reference"><a href="#cite_note-dericqles-et-al-48">[48]</a></sup></li>
<li><i><a href="/enwiki/wiki/Massospondylus" title="Massospondylus">Massospondylus</a></i><sup id="cite_ref-reisz-et-al_49-0" class="reference"><a href="#cite_note-reisz-et-al-49">[49]</a></sup></li>
<li><i><a href="/enwiki/wiki/Maiasaura" title="Maiasaura">Maiasaura</a></i></li>
<li><i><a href="/enwiki/wiki/Troodon" title="Troodon">Troodon</a></i><sup id="cite_ref-horner-weishampel_50-0" class="reference"><a href="#cite_note-horner-weishampel-50">[50]</a></sup></li></ul>
</div>
<h2><span class="mw-headline" id="Taphonomy">Taphonomy</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=11" title="Edit section: Taphonomy">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1033289096"/><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/enwiki/wiki/Egg_taphonomy" title="Egg taphonomy">Egg taphonomy</a></div>
<p>The formation of fossil eggs begins with the original egg itself. Not all eggs that end up fossilizing experience the death of their embryo beforehand. Fossil eggs with open tops are common and could result from the preservation of eggs that hatched successfully.<sup id="cite_ref-enbd-fossilize-112_51-0" class="reference"><a href="#cite_note-enbd-fossilize-112-51">[51]</a></sup> Dinosaur eggs whose embryos died were likely victims of similar causes to those that kill embryos in modern reptile and bird eggs. Typical causes of death include congenital problems, diseases, <a href="/enwiki/wiki/Suffocation" class="mw-redirect" title="Suffocation">suffocation</a> from being buried too deep, inimical temperatures, or too much or too little water.<sup id="cite_ref-enbd-fossilize-113_52-0" class="reference"><a href="#cite_note-enbd-fossilize-113-52">[52]</a></sup>
</p><p>Whether or not hatching was successful, burial would begin with sediments gradually entering any large openings in the shell.<sup id="cite_ref-enbd-fossilize-112_51-1" class="reference"><a href="#cite_note-enbd-fossilize-112-51">[51]</a></sup> Even intact eggs are likely to fill with sediment once they crack under the strain of deep burial. Sometimes, though, fossilization can begin fast enough to prevent the eggs from being cracked. If the water table is high enough dissolved minerals like calcite can percolate through the pores of the eggshell. When the egg is completely filled it can become sturdy enough to withstand the weight of the overlying sediments.<sup id="cite_ref-enbd-fossilize-113_52-1" class="reference"><a href="#cite_note-enbd-fossilize-113-52">[52]</a></sup> Not all fossil egg specimens are of complete specimens, however. Individual pieces of eggshell are much more robust than the entire egg and can be transported intact long distances from where they were originally laid.<sup id="cite_ref-enbd-fossilize-108_53-0" class="reference"><a href="#cite_note-enbd-fossilize-108-53">[53]</a></sup>
</p><p>When the egg is buried deeply enough, the bacteria decomposing it no longer have access to oxygen and need to power their metabolisms with different substances. These physiological changes in the decomposers also alter the local environment in a way that allows certain minerals to be deposited, while others remain in solution.<sup id="cite_ref-enbd-fossilize-113_52-2" class="reference"><a href="#cite_note-enbd-fossilize-113-52">[52]</a></sup> Generally, however, a fossilizing egg's shell keeps the same calcite it had in life, which allows scientists to study its original structure millions of years after the developing dinosaur hatched or died.<sup id="cite_ref-enbd-fossilize-114_54-0" class="reference"><a href="#cite_note-enbd-fossilize-114-54">[54]</a></sup> However, eggs can also sometimes be altered after burial. This process is called <a href="/enwiki/wiki/Diagenesis" title="Diagenesis">diagenesis</a>.<sup id="cite_ref-enbd-fossilize-114_54-1" class="reference"><a href="#cite_note-enbd-fossilize-114-54">[54]</a></sup> One form of diagenesis is a microscopic <a href="/enwiki/wiki/Hatching#Variations" title="Hatching">cross-hatched</a> pattern imposed on the eggshell by the pressure of being buried deeply.<sup id="cite_ref-enbd-fossilize-114-115_55-0" class="reference"><a href="#cite_note-enbd-fossilize-114-115-55">[55]</a></sup> If the pressure gets severe enough, sometimes the eggshell's internal microscopic structure can be completely destroyed. Diagenesis can also happen chemically in addition to physically. The chemical conditions of a decomposing egg can make it easy for silica to be incorporated into eggshell and damage its structure. When iron-bearing substances alter eggshell it can be obvious because compounds like <a href="/enwiki/wiki/Hematite" title="Hematite">hematite</a>, <a href="/enwiki/wiki/Pyrite" title="Pyrite">pyrite</a>, and <a href="/enwiki/wiki/Iron_sulfide" title="Iron sulfide">iron sulfide</a> can turn the shell blackish or rusty colors.<sup id="cite_ref-enbd-fossilize-115_56-0" class="reference"><a href="#cite_note-enbd-fossilize-115-56">[56]</a></sup>
</p>
<h3><span class="mw-headline" id="Depositional_environments">Depositional environments</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=12" title="Edit section: Depositional environments">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p>Dinosaur eggs are known from a variety of depositional environments.
</p><p><b><a href="/enwiki/wiki/Beach_sands" class="mw-redirect" title="Beach sands">Beach sands</a>:</b> Beach sands were a good place for dinosaurs to lay their eggs because the sand would be effective at absorbing and holding enough heat to incubate the eggs. One ancient beach deposit in northeastern Spain actually preserves about 300,000 fossil dinosaur eggs.<sup id="cite_ref-enbd-fossilize-111_57-0" class="reference"><a href="#cite_note-enbd-fossilize-111-57">[57]</a></sup>
</p><p><b><a href="/enwiki/wiki/Floodplains" class="mw-redirect" title="Floodplains">Floodplains</a>:</b> Dinosaurs often laid their eggs on ancient floodplains. The <a href="/enwiki/wiki/Mudstone" title="Mudstone">mudstones</a> deposited at these sites are therefore excellent sources of dinosaur egg fossils.<sup id="cite_ref-enbd-fossilize-108_53-1" class="reference"><a href="#cite_note-enbd-fossilize-108-53">[53]</a></sup>
</p><p><b><a href="/enwiki/wiki/Sand_dunes" class="mw-redirect" title="Sand dunes">Sand dunes</a>:</b> Many dinosaur eggs have been recovered from sandstone deposits that formed in the ancient dune fields of what are now northern China and Mongolia.<sup id="cite_ref-enbd-fossilize-110_58-0" class="reference"><a href="#cite_note-enbd-fossilize-110-58">[58]</a></sup> The presence of <i><a href="/enwiki/wiki/Oviraptor" title="Oviraptor">Oviraptor</a></i> preserved in their life brooding position suggests that the eggs, nests, and parents may have been rapidly buried by sandstorms.<sup id="cite_ref-enbd-fossilize-111_57-1" class="reference"><a href="#cite_note-enbd-fossilize-111-57">[57]</a></sup>
</p>
<h2><span class="mw-headline" id="Excavation_and_preparation">Excavation and preparation</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=13" title="Edit section: Excavation and preparation">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<p>Usually the first evidence of fossil dinosaur eggs to be discovered are shell fragments that have eroded away from the original eggs and been transported downhill by the elements.<sup id="cite_ref-enbd-collecting-115_1-1" class="reference"><a href="#cite_note-enbd-collecting-115-1">[1]</a></sup> If the source eggs can be found the area must be examined for more unexposed eggs. If the paleontologists are fortunate enough to have found a nest, the number and arrangement of the eggs must be estimated. Excavation must proceed to significant depth since many dinosaur nests include multiple layers of eggs. As the underside of the nest is excavated, it would be covered by material like newspaper, tin foil, or tissue. Afterwards, the entire block is covered in multiple layers of plaster-soaked strips of burlap. When the plaster is dried, the block is undercut the rest of the way and turned over.<sup id="cite_ref-enbd-collecting-117_59-0" class="reference"><a href="#cite_note-enbd-collecting-117-59">[59]</a></sup>
</p><p>The fine work of cleaning the egg fossils is performed in a laboratory. Preparation usually begins from the underside of the block, which tends to be the best preserved.<sup id="cite_ref-enbd-collecting-117_59-1" class="reference"><a href="#cite_note-enbd-collecting-117-59">[59]</a></sup> Because of their fragility, cleaning fossil eggs requires patience and skill.<sup id="cite_ref-enbd-collecting-117-118_60-0" class="reference"><a href="#cite_note-enbd-collecting-117-118-60">[60]</a></sup> Scientists use delicate instruments like dental picks, needles, small <a href="/enwiki/wiki/Pneumatic" class="mw-redirect" title="Pneumatic">pneumatic</a> engraving tools, and <a href="/enwiki/wiki/X-Acto" title="X-Acto">X-Acto</a> knives.<sup id="cite_ref-enbd-collecting-117_59-2" class="reference"><a href="#cite_note-enbd-collecting-117-59">[59]</a></sup> Scientists must determine at what point to stop cleaning based on their own criteria. If eggs are fully extracted they can be more fully studied individually at the cost of information regarding the spatial relationships between eggs or if the eggs had hatched. Commercial fossil dealers tend to expose only the bottom of the eggs since the topsides might be damaged by hatching and therefore less visually appealing to potential customers.<sup id="cite_ref-enbd-collecting-118_61-0" class="reference"><a href="#cite_note-enbd-collecting-118-61">[61]</a></sup>
</p>
<h2><span class="mw-headline" id="Research_techniques">Research techniques</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=14" title="Edit section: Research techniques">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<h3><span class="mw-headline" id="Acid_dissolution">Acid dissolution</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=15" title="Edit section: Acid dissolution">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p>Acids can be used to learn more about fossil eggs. Diluted <a href="/enwiki/wiki/Acetic_acid" title="Acetic acid">acetic acid</a> or <a href="/enwiki/wiki/EDTA" class="mw-redirect" title="EDTA">EDTA</a> can be used to expose the microstructure of shell that has been damaged by weathering. Acids are also used to extract embryo skeletons from the egg encasing them.<sup id="cite_ref-enbd-tools-128_62-0" class="reference"><a href="#cite_note-enbd-tools-128-62">[62]</a></sup> Even fossilized soft tissue like muscle and cartilage as well as fat globules from the original <a href="/enwiki/wiki/Egg_yolk" class="mw-redirect" title="Egg yolk">egg yolk</a> can be uncovered using this method.<sup id="cite_ref-enbd-tools-130_63-0" class="reference"><a href="#cite_note-enbd-tools-130-63">[63]</a></sup> Amateur paleontologist <a href="/enwiki/wiki/Terry_Manning" title="Terry Manning">Terry Manning</a> has been credited with groundbreaking work developing this technique.<sup id="cite_ref-64" class="reference"><a href="#cite_note-64">[64]</a></sup> First, the paleontologist must submerge the egg in a very dilute phosphoric acid bath. Since the acid solution can penetrate the egg, every few days the specimen must be soaked in distilled water to prevent the acid from damaging the embryo before it is even exposed. If embryonic fossil bone is revealed after drying from the water bath, the exposed fossils must be delicately cleaned with fine instruments like needles and paint brushes. The exposed bone is then coated with plastic preservatives like <a href="/enwiki/w/index.php?title=Acryloid_B67&action=edit&redlink=1" class="new" title="Acryloid B67 (page does not exist)">Acryloid B67</a>, <a href="/enwiki/w/index.php?title=Paraloid_B72&action=edit&redlink=1" class="new" title="Paraloid B72 (page does not exist)">Paraloid B72</a>, or <a href="/enwiki/w/index.php?title=Vinac_B15&action=edit&redlink=1" class="new" title="Vinac B15 (page does not exist)">Vinac B15</a> to protect it from the acid when submerged for another round. The complete process can take months before the whole embryo is revealed.<sup id="cite_ref-enbd-tools-128_62-1" class="reference"><a href="#cite_note-enbd-tools-128-62">[62]</a></sup> Even then only about 20% of the eggs subjected to the process reveal any embryo fossils at all.<sup id="cite_ref-enbd-tools-128-130_65-0" class="reference"><a href="#cite_note-enbd-tools-128-130-65">[65]</a></sup>
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<h3><span class="mw-headline" id="CAT_scans">CAT scans</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=16" title="Edit section: CAT scans">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p><a href="/enwiki/wiki/CAT_scans" class="mw-redirect" title="CAT scans">CAT scans</a> can be used to infer the 3D structure of a fossil egg's interior by compiling images taken of slices through the egg in small regular increments. Scientists have tried to use CAT scans to look for embryo fossils contained inside the egg without having to damage the egg itself by physically extracting them. However, as of Ken Carpenter's 1999 book on dinosaur eggs, <i>Eggs, Nests, and Baby Dinosaurs</i>, all alleged embryos discovered using this method were actually false alarms. Variations in the type of infilling mineral or cement binding the infilling sediment into rock sometimes resemble bones in CAT scan images. Sometimes eggshell fragments that fell back into the egg when it hatched have been mistaken for embryonic bones.<sup id="cite_ref-enbd-tools-128_62-2" class="reference"><a href="#cite_note-enbd-tools-128-62">[62]</a></sup><sup id="cite_ref-enbd-collecting-7-11_66-0" class="reference"><a href="#cite_note-enbd-collecting-7-11-66">[66]</a></sup> The use of CAT scans to search for embryonic remains is actually conceptually flawed since embryonic bones have not yet <a href="/enwiki/wiki/Ossification" title="Ossification">mineralized</a>. Since the infilling sediment is their only source of minerals they will be preserved at basically the same density and therefore have poor visibility in the scan. The validity of this issue has been confirmed by performing Cat scans on fossil eggs known to have embryos inside and noting their poor visibility in the scan images. The only truly reliable way to discover a dinosaur embryo is to cut the egg open or dissolve some of its eggshell away.<sup id="cite_ref-enbd-tools-128_62-3" class="reference"><a href="#cite_note-enbd-tools-128-62">[62]</a></sup>
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<h3><span class="mw-headline" id="Cathodoluminescence">Cathodoluminescence</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=17" title="Edit section: Cathodoluminescence">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p><a href="/enwiki/wiki/Cathodoluminescence" title="Cathodoluminescence">Cathodoluminescence</a> is the most important tool paleontologists have for revealing whether or not the <a href="/enwiki/wiki/Calcium" title="Calcium">calcium</a> in fossil eggshell has been altered.<sup id="cite_ref-enbd-tools-133_67-0" class="reference"><a href="#cite_note-enbd-tools-133-67">[67]</a></sup> Calcite in eggshell is either pure or rich in <a href="/enwiki/wiki/Calcium_carbonate" title="Calcium carbonate">calcium carbonate</a>. However, the calcite composing the egg can be altered after burial to include significant calcium content. Cathodoluminescence causes calcite altered in this fashion to glow orange.<sup id="cite_ref-enbd-tools-134_68-0" class="reference"><a href="#cite_note-enbd-tools-134-68">[68]</a></sup>
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<h3><span class="mw-headline" id="Gel_electrophoresis">Gel electrophoresis</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=18" title="Edit section: Gel electrophoresis">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p><a href="/enwiki/wiki/Gel_electrophoresis" title="Gel electrophoresis">Gel electrophoresis</a> has been used in attempts to identify the <a href="/enwiki/wiki/Amino_acids" class="mw-redirect" title="Amino acids">amino acids</a> present in the organic components of dinosaur eggshell. Contact with human skin can contaminate eggs with foreign amino acids, so only untouched eggs can be investigated using this technique. <a href="/enwiki/wiki/EDTA" class="mw-redirect" title="EDTA">EDTA</a> can be used to dissolve the calcite of the eggshell while leaving the shell's organic content intact. The resultant organic residue would be blended and then implanted into <a href="/enwiki/wiki/Gel" title="Gel">gel</a>. Electricity would then be run through the sample, causing the amino acids to migrate through the gel until they stop at levels determined by their physical properties. <a href="/enwiki/w/index.php?title=Protein_silver_stain&action=edit&redlink=1" class="new" title="Protein silver stain (page does not exist)">Protein silver stain</a> is then used to dye the amino acids and make them visible.<sup id="cite_ref-enbd-tools-133_67-1" class="reference"><a href="#cite_note-enbd-tools-133-67">[67]</a></sup> The bands of amino acids from the dinosaur eggs can then be compared with the banding of samples with known composition for identification.<sup id="cite_ref-enbd-tools-133_67-2" class="reference"><a href="#cite_note-enbd-tools-133-67">[67]</a></sup>
</p><p>Gel electrophoresis is not necessarily a perfect means of discovering the amino acid composition of dinosaur eggshell because sometimes the amount or type of amino acids present could be altered during or after preservation. One potential confounding factor would be the heating of deeply buried egg fossils, which can break down amino acids. Another potential source of error is groundwater, which can leach away amino acids. These issues cast doubt as to whether the results these sorts of studies give are reliable as the actual composition of the eggshell's organic material in life. However, studies applying these techniques have made suggestive findings, including amino acid profiles in dinosaur eggs similar to those in modern birds.<sup id="cite_ref-enbd-tools-133_67-3" class="reference"><a href="#cite_note-enbd-tools-133-67">[67]</a></sup>
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<h3><span class="mw-headline" id="Geneva_lens_measure">Geneva lens measure</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=19" title="Edit section: Geneva lens measure">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p>The <a href="/enwiki/w/index.php?title=Geneva_Lens_Measure&action=edit&redlink=1" class="new" title="Geneva Lens Measure (page does not exist)">Geneva Lens Measure</a> is a device used to measure curved surfaces. It is most commonly used by <a href="/enwiki/wiki/Opticians" class="mw-redirect" title="Opticians">opticians</a> to measure lenses but can also be used by paleontologists to estimate the life size of dinosaur eggs from shell fragments. The instrument can be used to help estimate the size of fossil eggshells by measuring their curved surfaces. Since most eggs aren't perfectly round measurements from multiple parts of the egg with varying shell curvatures may be needed to get a full idea of the egg's size. Ideally an eggshell fragment being used to estimate the full size of an egg should be more than 3 cm long. Smaller eggshell fragments are better suited to other methods of study, like the <a href="/enwiki/w/index.php?title=Obrig_radius_dial_gauge&action=edit&redlink=1" class="new" title="Obrig radius dial gauge (page does not exist)">Obrig radius dial gauge</a>. The Geneva Lens measure gives units in <a href="/enwiki/wiki/Diopters" class="mw-redirect" title="Diopters">diopters</a> which must be converted to the radius in millimeters. Use of the Geneva Lens Measure to estimate the size of a fossil egg was first done by <a href="/enwiki/wiki/Sauer" title="Sauer">Sauer</a> on fossil ostrich eggs.<sup id="cite_ref-enbd-tools-134_68-1" class="reference"><a href="#cite_note-enbd-tools-134-68">[68]</a></sup>
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<h3><span class="mw-headline" id="Light_microscopy">Light microscopy</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=20" title="Edit section: Light microscopy">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p><a href="/enwiki/wiki/Light_microscopy" class="mw-redirect" title="Light microscopy">Light microscopy</a> can be used to magnify the structure of dinosaur eggshell for scientific research. To do so an eggshell fragment must be embedded in <a href="/enwiki/wiki/Epoxy" title="Epoxy">epoxy</a> <a href="/enwiki/wiki/Resin" title="Resin">resin</a> and sliced into a thin section with a thin-bladed <a href="/enwiki/w/index.php?title=Rock_saw&action=edit&redlink=1" class="new" title="Rock saw (page does not exist)">rock saw</a>. This basic method was invented by French paleontologist <a href="/enwiki/wiki/Paul_Gervais" title="Paul Gervais">Paul Gervais</a> and has remained almost unchanged ever since. Horizontally cut thin sections are called tangential thin sections while vertically cut thin sections are called radial sections. Regardless of direction, the sample must be abraded by fine-grit <a href="/enwiki/wiki/Sand_paper" class="mw-redirect" title="Sand paper">sand</a> or <a href="/enwiki/wiki/Emery_paper" title="Emery paper">emery paper</a> until it is <a href="/enwiki/wiki/Translucent" class="mw-redirect" title="Translucent">translucent</a>. Then the structure of the shell's <a href="/enwiki/wiki/Calcite" title="Calcite">calcite crystals</a> or pores can be examined under a <a href="/enwiki/wiki/Petrographic_microscope" title="Petrographic microscope">petrographic microscope</a>.<sup id="cite_ref-enbd-tools-122_69-0" class="reference"><a href="#cite_note-enbd-tools-122-69">[69]</a></sup> The calcite crystal structure of dinosaur eggshell can be classified by their effect on <a href="/enwiki/wiki/Polarized_light" class="mw-redirect" title="Polarized light">polarized light</a>. Calcite is capable of acting as a polarizing light filter.<sup id="cite_ref-enbd-tools-124_70-0" class="reference"><a href="#cite_note-enbd-tools-124-70">[70]</a></sup> When a microscopic thin section sample is rotated relative to polarized light it can eventually block all the light and seem opaque. This phenomenon is called extinction. Different varieties of dinosaur eggs with their different calcite crystal structures have different light extinction properties that can be used to identify and distinguish even eggs that seem very similar on the surface.<sup id="cite_ref-enbd-tools-125_71-0" class="reference"><a href="#cite_note-enbd-tools-125-71">[71]</a></sup> To reconstruct the three-dimensional structures of the shell's pore channels scientists require a series of multiple radial sections.<sup id="cite_ref-enbd-tools-122_69-1" class="reference"><a href="#cite_note-enbd-tools-122-69">[69]</a></sup>
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<h3><span class="mw-headline" id="Scanning_electron_microscopy">Scanning electron microscopy</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=21" title="Edit section: Scanning electron microscopy">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p><a href="/enwiki/wiki/Scanning_electron_microscopy" class="mw-redirect" title="Scanning electron microscopy">Scanning electron microscopy</a> is used to view dinosaur eggshell under even greater magnification than is possible with light microscopy. However, this does not mean that scanning electron microscopy is necessarily the superior research method. Since both techniques provide differing amounts and types of information they can be used together synergistically to provide a more complete understanding of the specimen under scrutiny. Eggshell specimens best suited for scanning electron microscopy are those recently broken because such a break will usually occur along the plane of the eggshell's calcite crystal lattice. First, a small specimen would be covered with a very thin layer of <a href="/enwiki/wiki/Gold" title="Gold">gold</a> or <a href="/enwiki/wiki/Platinum" title="Platinum">platinum</a>. The specimen would then be bombarded with <a href="/enwiki/wiki/Electrons" class="mw-redirect" title="Electrons">electrons</a>. The electrons bounce back off the metal and due to their small size, can be used to form a detailed image of the specimen.<sup id="cite_ref-enbd-tools-125_71-1" class="reference"><a href="#cite_note-enbd-tools-125-71">[71]</a></sup>
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<h3><span class="mw-headline" id="Mass_spectrometry">Mass spectrometry</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=22" title="Edit section: Mass spectrometry">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p><a href="/enwiki/wiki/Mass_spectrometry" title="Mass spectrometry">Mass spectrometry</a> is a method for determining eggshell composition that uses a device called a mass spectrometer. First, the eggshell sample must be powdered and placed in the mass spectrometer's vacuum chamber.<sup id="cite_ref-enbd-tools-130_63-1" class="reference"><a href="#cite_note-enbd-tools-130-63">[63]</a></sup> The powder is vaporized by the heat of an intense laser beam. A stream of electrons then bombard the gaseous eggshell molecules, which breaks down the molecules in the eggshell and imbues them with a positive charge. A magnetic field then sorts them by mass before they are detected by the spectrometer.<sup id="cite_ref-enbd-tools-131_72-0" class="reference"><a href="#cite_note-enbd-tools-131-72">[72]</a></sup> One application of mass spectrometry has been to study the isotope ratios of dinosaur eggshell in order to ascertain their diets and living conditions. However this research is complicated by the fact that isotope ratios can be altered post mortem before or during fossilization. Bacterial decomposition can alter <a href="/enwiki/wiki/Carbon_isotope" class="mw-redirect" title="Carbon isotope">carbon isotope</a> ratios in eggs and <a href="/enwiki/wiki/Groundwater" title="Groundwater">groundwater</a> can alter the <a href="/enwiki/wiki/Oxygen_isotope" class="mw-redirect" title="Oxygen isotope">oxygen isotope</a> ratios of eggshell.<sup id="cite_ref-enbd-tools-132_73-0" class="reference"><a href="#cite_note-enbd-tools-132-73">[73]</a></sup>
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<h3><span class="mw-headline" id="X_rays">X rays</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=23" title="Edit section: X rays">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p>X-ray equipment, like CAT scans, are used to study the interior of fossil eggs. Unlike CAT scans, x-ray imaging condenses the entire interior of the egg into a single two-dimensional image rather than a series of images documenting the interior in three dimensions. X-ray imaging in the context of dinosaur research has generally been used to look for evidence of embryonic fossils contained inside the egg. However, as of Kenneth Carpenter's 1999 book <i>Eggs, Nests, and Baby Dinosaurs</i>, all putative embryos discovered using x-rays have been misidentifications. This is because the use of x-rays to find embryos is conceptually flawed. Embryo bones are incompletely developed and will generally lack their own mineral content, as such the only source of minerals for these bones is the sediment that fills the egg after burial. The fossilized bones will therefore have the same density as the sediment filling the interior of the egg which served as the source for their mineral content and will be poorly visible in an x-ray image. So far the only reliable method for examining embryonic fossils preserved in dinosaur eggs is to physically extract them through means such as acid dissolution.<sup id="cite_ref-enbd-tools-128_62-4" class="reference"><a href="#cite_note-enbd-tools-128-62">[62]</a></sup>
</p><p>X-rays can be used to chemically analyze dinosaur eggshell. This technique requires pure shell samples, so the fossil must be completely free of its surrounding rock matrix. The shell must then be further cleaned by an <a href="/enwiki/wiki/Ultrasonic_cleaning" title="Ultrasonic cleaning">ultrasonic bath</a>. The sample can then be bombarded by electrons emitted by the same sort of probe used by scanning electron microscopes. Upon impact with the samples x-rays are emitted that can be used to identify the composition of the shell.<sup id="cite_ref-enbd-tools-130_63-2" class="reference"><a href="#cite_note-enbd-tools-130-63">[63]</a></sup>
</p><p><a href="/enwiki/wiki/X-ray_diffraction" class="mw-redirect" title="X-ray diffraction">X-ray diffraction</a> is a method for determining eggshell composition that uses X-rays to directly bombard powdered eggshell. Upon impact some of the x-rays will be diffracted at different angles and intensities depending on the specific elements present in the eggshell.<sup id="cite_ref-enbd-tools-130_63-3" class="reference"><a href="#cite_note-enbd-tools-130-63">[63]</a></sup>
</p><p><b>Allosterics</b>
</p><p>In order to test out how allosterics played a part in dinosaur egg size, scientists used modern day animal species such as birds, crocodiles, and tortoises in their experiment. They set the bird group as representing the theropods with the reptiles representing the sauropod group. The laid eggs of each species where compared with one another over the course of the study as well as against the fossilized eggs. The results that was retrieved from the experiment was that while sauropods laid smaller eggs in greater amounts each year, dinosaur of the theropod group was revealed to lay larger eggs less frequently over the years, similar to modern birds today.
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<h2><span class="mw-headline" id="Footnotes">Footnotes</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=24" title="Edit section: Footnotes">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
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<ol class="references">
<li id="cite_note-enbd-collecting-115-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-collecting-115_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-collecting-115_1-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"Collecting Eggs," Carpenter (1999); page 115.</span>
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<li id="cite_note-enbd-fake-118-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-fake-118_2-0">^</a></b></span> <span class="reference-text">"Fake Eggs," Carpenter (1999); page 118.</span>
</li>
<li id="cite_note-enbd-fake-121-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-fake-121_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-fake-121_3-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"Fake Eggs," Carpenter (1999); page 121.</span>
</li>
<li id="cite_note-enbd-fake-120-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-fake-120_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-fake-120_4-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-enbd-fake-120_4-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-enbd-fake-120_4-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-enbd-fake-120_4-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-enbd-fake-120_4-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-enbd-fake-120_4-6"><sup><i><b>g</b></i></sup></a></span> <span class="reference-text">"Fake Eggs," Carpenter (1999); page 120.</span>
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<li id="cite_note-enbd-fake-120-121-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-fake-120-121_5-0">^</a></b></span> <span class="reference-text">"Fake Eggs," Carpenter (1999); pages 120–121.</span>
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<li id="cite_note-enbd-fake-119-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-fake-119_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-fake-119_6-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"Fake Eggs," Carpenter (1999); page 119.</span>
</li>
<li id="cite_note-enbd-fake-119-120-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-fake-119-120_7-0">^</a></b></span> <span class="reference-text">"Fake Eggs," Carpenter (1999); pages 119–120.</span>
</li>
<li id="cite_note-Making_an_Egg-8"><span class="mw-cite-backlink">^ <a href="#cite_ref-Making_an_Egg_8-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Making_an_Egg_8-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Making_an_Egg_8-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Making_an_Egg_8-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-Making_an_Egg_8-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1133582631">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free a,.mw-parser-output .citation .cs1-lock-free a{background:url("/upwiki/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited a,.mw-parser-output .id-lock-registration a,.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:url("/upwiki/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription a,.mw-parser-output .citation .cs1-lock-subscription a{background:url("/upwiki/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("/upwiki/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:#d33}.mw-parser-output .cs1-visible-error{color:#d33}.mw-parser-output .cs1-maint{display:none;color:#3a3;margin-left:0.3em}.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}</style><cite id="CITEREFCarpenter1999" class="citation book cs1">Carpenter, Kenneth (1999). "Making an Egg". <a rel="nofollow" class="external text" href="https://archive.org/details/isbn_9780253334978/page/85"><i>Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)</i></a>. Bloomington, Indiana: Indiana University Press. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/isbn_9780253334978/page/85">85–107</a>. <a href="/enwiki/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0-253-33497-8" title="Special:BookSources/978-0-253-33497-8"><bdi>978-0-253-33497-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Making+an+Egg&rft.btitle=Eggs%2C+Nests%2C+and+Baby+Dinosaurs%3A+A+Look+at+Dinosaur+Reproduction+%28Life+of+the+Past%29&rft.place=Bloomington%2C+Indiana&rft.pages=85-107&rft.pub=Indiana+University+Press&rft.date=1999&rft.isbn=978-0-253-33497-8&rft.aulast=Carpenter&rft.aufirst=Kenneth&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fisbn_9780253334978%2Fpage%2F85&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-How_to_Study-9"><span class="mw-cite-backlink">^ <a href="#cite_ref-How_to_Study_9-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-8"><sup><i><b>i</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-9"><sup><i><b>j</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-10"><sup><i><b>k</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-11"><sup><i><b>l</b></i></sup></a> <a href="#cite_ref-How_to_Study_9-12"><sup><i><b>m</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFCarpenter1999" class="citation book cs1">Carpenter, Kenneth (1999). "How to Study a Fossil Egg". <a rel="nofollow" class="external text" href="https://archive.org/details/isbn_9780253334978/page/122"><i>Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)</i></a>. Bloomington, Indiana: Indiana University Press. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/isbn_9780253334978/page/122">122–144</a>. <a href="/enwiki/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0-253-33497-8" title="Special:BookSources/978-0-253-33497-8"><bdi>978-0-253-33497-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=How+to+Study+a+Fossil+Egg&rft.btitle=Eggs%2C+Nests%2C+and+Baby+Dinosaurs%3A+A+Look+at+Dinosaur+Reproduction+%28Life+of+the+Past%29&rft.place=Bloomington%2C+Indiana&rft.pages=122-144&rft.pub=Indiana+University+Press&rft.date=1999&rft.isbn=978-0-253-33497-8&rft.aulast=Carpenter&rft.aufirst=Kenneth&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fisbn_9780253334978%2Fpage%2F122&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-UCMP-10"><span class="mw-cite-backlink">^ <a href="#cite_ref-UCMP_10-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-UCMP_10-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-UCMP_10-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-UCMP_10-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-UCMP_10-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-UCMP_10-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-UCMP_10-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-UCMP_10-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-UCMP_10-8"><sup><i><b>i</b></i></sup></a></span> <span class="reference-text">Laura E. Wilson, Karen Chin, Frankie D. Jackson, and Emily S. Bray. <a rel="nofollow" class="external text" href="http://www.ucmp.berkeley.edu/science/eggshell/eggshell2.php">II. Eggshell morphology and structure</a>. <i>UCMP Online Exhibits: Fossil Eggshell</i></span>
</li>
<li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFDauphin1990" class="citation journal cs1">Dauphin, Y. (1990). "Comparative microstructural studies of eggshells. 1. Dinosaurs of the Southern France". <i>Revue de Paléobiologie</i>. <b>9</b>: 127–133.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Revue+de+Pal%C3%A9obiologie&rft.atitle=Comparative+microstructural+studies+of+eggshells.+1.+Dinosaurs+of+the+Southern+France&rft.volume=9&rft.pages=127-133&rft.date=1990&rft.aulast=Dauphin&rft.aufirst=Y.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFDauphin1990" class="citation journal cs1 cs1-prop-long-vol">Dauphin, Y. (1990). "Incidence de l'état diagénétique des coquilles d'oeufs de dinosaures sur la reconnaissance des morphotypes - exemple du Bassin d'Aix en Provence". <i>C. R. Acad. Sci. Paris</i>. sér/ II, 310: 849–954.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=C.+R.+Acad.+Sci.+Paris&rft.atitle=Incidence+de+l%27%C3%A9tat+diag%C3%A9n%C3%A9tique+des+coquilles+d%27oeufs+de+dinosaures+sur+la+reconnaissance+des+morphotypes+-+exemple+du+Bassin+d%27Aix+en+Provence&rft.volume=s%C3%A9r%2F+II%2C+310&rft.pages=849-954&rft.date=1990&rft.aulast=Dauphin&rft.aufirst=Y.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFDauphinJaeger1991" class="citation journal cs1">Dauphin, Y.; Jaeger, J.J. (1991). "Implications de l'analyse microstructurale et géochimique des œufs de dinosaures de la cairanne (Bassin d'Aix en Provence, France, Rognacien inférieur)". <i>Paläontologische Zeitschrift</i>. <b>65</b> (3–4): 391–404. <a href="/enwiki/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fbf02989853">10.1007/bf02989853</a>. <a href="/enwiki/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="/enwiki//www.worldcat.org/issn/0031-0220">0031-0220</a>. <a href="/enwiki/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:129041143">129041143</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Pal%C3%A4ontologische+Zeitschrift&rft.atitle=Implications+de+l%27analyse+microstructurale+et+g%C3%A9ochimique+des+%C5%93ufs+de+dinosaures+de+la+cairanne+%28Bassin+d%27Aix+en+Provence%2C+France%2C+Rognacien+inf%C3%A9rieur%29&rft.volume=65&rft.issue=3%E2%80%934&rft.pages=391-404&rft.date=1991&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A129041143%23id-name%3DS2CID&rft.issn=0031-0220&rft_id=info%3Adoi%2F10.1007%2Fbf02989853&rft.aulast=Dauphin&rft.aufirst=Y.&rft.au=Jaeger%2C+J.J.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-Simon_2014-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-Simon_2014_14-0">^</a></b></span> <span class="reference-text">Simon, D. J. (2014). "<a rel="nofollow" class="external text" href="http://scholarworks.montana.edu/xmlui/bitstream/handle/1/8693/SimonD0814.pdf?sequence=1">Giant Dinosaur (theropod) Eggs of the Oogenus Macroelongatoolithus (Elongatoolithidae) from Southeastern Idaho: Taxonomic, Paleobiogeographic, and Reproductive Implications.</a>" (Doctoral dissertation, Montana State University, Bozeman).</span>
</li>
<li id="cite_note-M1996-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-M1996_15-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFMikhailov1996" class="citation journal cs1">Mikhailov, Konstantin (1996). "Bird Eggs in the Upper Cretaceous of Mongolia". <i>Paleontological Journal</i>. <b>30</b> (1): 114–116.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Paleontological+Journal&rft.atitle=Bird+Eggs+in+the+Upper+Cretaceous+of+Mongolia&rft.volume=30&rft.issue=1&rft.pages=114-116&rft.date=1996&rft.aulast=Mikhailov&rft.aufirst=Konstantin&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-Vianey-Liaud_and_Lopez-Martinez_1997-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-Vianey-Liaud_and_Lopez-Martinez_1997_16-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFVianey-LiaudLopez-Martinez1997" class="citation journal cs1">Vianey-Liaud, Monique; Lopez-Martinez, Nieves (1997). <a rel="nofollow" class="external text" href="https://eprints.ucm.es/id/eprint/69803/1/3Vianey%26LopezM97-1.pdf">"Late Cretaceous Dinosaur Eggshells from the Tremp Basin, Southern Pyrenees, Lleida, Spain"</a> <span class="cs1-format">(PDF)</span>. <i>Journal of Paleontology</i>. <b>71</b> (6): 1157–1171. <a href="/enwiki/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1017%2Fs002233600003609x">10.1017/s002233600003609x</a>. <a href="/enwiki/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:131405598">131405598</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Paleontology&rft.atitle=Late+Cretaceous+Dinosaur+Eggshells+from+the+Tremp+Basin%2C+Southern+Pyrenees%2C+Lleida%2C+Spain&rft.volume=71&rft.issue=6&rft.pages=1157-1171&rft.date=1997&rft_id=info%3Adoi%2F10.1017%2Fs002233600003609x&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A131405598%23id-name%3DS2CID&rft.aulast=Vianey-Liaud&rft.aufirst=Monique&rft.au=Lopez-Martinez%2C+Nieves&rft_id=https%3A%2F%2Feprints.ucm.es%2Fid%2Feprint%2F69803%2F1%2F3Vianey%2526LopezM97-1.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-Intro-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-Intro_17-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFCarpenterHirschHorner1994" class="citation book cs1">Carpenter, Kenneth; Hirsch, Karl; Horner, John (1994). "Introduction". In Carpenter, Kenneth; Hirsch, Karl; Horner, John (eds.). <i>Dinosaur Eggs and Babies</i>. Trumpington Street, Cambridge: University of Cambridge. pp. 1–11. <a href="/enwiki/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0-521-44342-5" title="Special:BookSources/978-0-521-44342-5"><bdi>978-0-521-44342-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Introduction&rft.btitle=Dinosaur+Eggs+and+Babies&rft.place=Trumpington+Street%2C+Cambridge&rft.pages=1-11&rft.pub=University+of+Cambridge&rft.date=1994&rft.isbn=978-0-521-44342-5&rft.aulast=Carpenter&rft.aufirst=Kenneth&rft.au=Hirsch%2C+Karl&rft.au=Horner%2C+John&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-UCMPV-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-UCMPV_18-0">^</a></b></span> <span class="reference-text">Laura E. Wilson, Karen Chin, Frankie D. Jackson, and Emily S. Bray. <a rel="nofollow" class="external text" href="http://www.ucmp.berkeley.edu/science/eggshell/eggshell2.php">V. Paleobiology and eggs</a>. <i>UCMP Online Exhibits: Fossil Eggshell</i></span>
</li>
<li id="cite_note-Nests-19"><span class="mw-cite-backlink">^ <a href="#cite_ref-Nests_19-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Nests_19-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Nests_19-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Nests_19-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFMoratallaPowell1994" class="citation book cs1">Moratalla, J.J.; Powell, J.E. (1994). "Dinosaur Nesting Patterns". In Carpenter, Kenneth; Hirsch, Karl; Horner, John (eds.). <i>Dinosaur Eggs and Babies</i>. The Pitt Building, Trumpington Street, Cambridge: Cambridge University Press. pp. 37–46.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Dinosaur+Nesting+Patterns&rft.btitle=Dinosaur+Eggs+and+Babies&rft.place=The+Pitt+Building%2C+Trumpington+Street%2C+Cambridge&rft.pages=37-46&rft.pub=Cambridge+University+Press&rft.date=1994&rft.aulast=Moratalla&rft.aufirst=J.J.&rft.au=Powell%2C+J.E.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-Soto-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-Soto_20-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFSotoPereaCambiaso2012" class="citation journal cs1">Soto, M.; Perea, D.; Cambiaso, A.V. (2012). <a rel="nofollow" class="external text" href="https://www.researchgate.net/publication/232399931">"First sauropod (Dinosauria: Saurischia) remains from the Guichón Formation, Late Cretaceous of Uruguay"</a>. <i>Journal of South American Earth Sciences</i>. <b>33</b> (1): 68–79. <a href="/enwiki/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2012JSAES..33...68S">2012JSAES..33...68S</a>. <a href="/enwiki/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.jsames.2011.08.003">10.1016/j.jsames.2011.08.003</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+South+American+Earth+Sciences&rft.atitle=First+sauropod+%28Dinosauria%3A+Saurischia%29+remains+from+the+Guich%C3%B3n+Formation%2C+Late+Cretaceous+of+Uruguay&rft.volume=33&rft.issue=1&rft.pages=68-79&rft.date=2012&rft_id=info%3Adoi%2F10.1016%2Fj.jsames.2011.08.003&rft_id=info%3Abibcode%2F2012JSAES..33...68S&rft.aulast=Soto&rft.aufirst=M.&rft.au=Perea%2C+D.&rft.au=Cambiaso%2C+A.V.&rft_id=https%3A%2F%2Fwww.researchgate.net%2Fpublication%2F232399931&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFMoreno-AzanzaBauluzCanudoGasca2016" class="citation journal cs1">Moreno-Azanza, Miguel; Bauluz, Blanca; Canudo, José Ignacio; Gasca, José Manuel; Fernández-Baldor, Fidel Torcida (2016). <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC4856302">"Combined Use of Electron and Light Microscopy Techniques Reveals False Secondary Shell Units in Megaloolithidae Eggshells"</a>. <i><a href="/enwiki/wiki/PLOS_ONE" class="mw-redirect" title="PLOS ONE">PLOS ONE</a></i> (published May 4, 2016). <b>11</b> (5): e0153026. <a href="/enwiki/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2016PLoSO..1153026M">2016PLoSO..1153026M</a>. <a href="/enwiki/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="cs1-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1371%2Fjournal.pone.0153026">10.1371/journal.pone.0153026</a></span>. <a href="/enwiki/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="cs1-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC4856302">4856302</a></span>. <a href="/enwiki/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//pubmed.ncbi.nlm.nih.gov/27144767">27144767</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=PLOS+ONE&rft.atitle=Combined+Use+of+Electron+and+Light+Microscopy+Techniques+Reveals+False+Secondary+Shell+Units+in+Megaloolithidae+Eggshells&rft.volume=11&rft.issue=5&rft.pages=e0153026&rft.date=2016&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4856302%23id-name%3DPMC&rft_id=info%3Apmid%2F27144767&rft_id=info%3Adoi%2F10.1371%2Fjournal.pone.0153026&rft_id=info%3Abibcode%2F2016PLoSO..1153026M&rft.aulast=Moreno-Azanza&rft.aufirst=Miguel&rft.au=Bauluz%2C+Blanca&rft.au=Canudo%2C+Jos%C3%A9+Ignacio&rft.au=Gasca%2C+Jos%C3%A9+Manuel&rft.au=Fern%C3%A1ndez-Baldor%2C+Fidel+Torcida&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4856302&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-basic-spherulitic-136-137-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-basic-spherulitic-136-137_22-0">^</a></b></span> <span class="reference-text">"Basic Types Eggshell: Spherulitic Basic Type," Carpenter (1999); pages 136-137.</span>
</li>
<li id="cite_note-basic-prismatic-137-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-basic-prismatic-137_23-0">^</a></b></span> <span class="reference-text">"Basic Types Eggshell: Prismatic Basic Type," Carpenter (1999); page 137.</span>
</li>
<li id="cite_note-ubristol-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-ubristol_24-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite class="citation cs2"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20140201213751/http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html"><i>What are dinosaur eggs?</i></a>, archived from <a rel="nofollow" class="external text" href="http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html">the original</a> on February 1, 2014</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=What+are+dinosaur+eggs%3F&rft_id=http%3A%2F%2Fpalaeo.gly.bris.ac.uk%2Fpalaeofiles%2Feggs%2Fdefault.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-DFG03-25"><span class="mw-cite-backlink">^ <a href="#cite_ref-DFG03_25-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-DFG03_25-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-DFG03_25-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-DFG03_25-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-DFG03_25-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-DFG03_25-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-DFG03_25-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-DFG03_25-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-DFG03_25-8"><sup><i><b>i</b></i></sup></a> <a href="#cite_ref-DFG03_25-9"><sup><i><b>j</b></i></sup></a> <a href="#cite_ref-DFG03_25-10"><sup><i><b>k</b></i></sup></a></span> <span class="reference-text">Glut (2003).</span>
</li>
<li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=82906">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67205">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67198">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=81056">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67185">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=81709">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-32">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67183">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-33">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=98798">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=65584">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-35">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67189">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-36"><span class="mw-cite-backlink"><b><a href="#cite_ref-36">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=56741">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-Lawver_et_al_2016-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-Lawver_et_al_2016_37-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFLawverJinJacksonWang2016" class="citation journal cs1">Lawver, Daniel R.; Jin, Xingsheng; Jackson, Frankie D.; Wang, Qiongying (2016). "An Avian Egg from the Lower Cretaceous (Albian) Liangtoutang Formation of Zhejiang Province, China". <i>Journal of Vertebrate Paleontology</i>. <b>36</b> (3): e1100631. <a href="/enwiki/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1080%2F02724634.2016.1100631">10.1080/02724634.2016.1100631</a>. <a href="/enwiki/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:88169746">88169746</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Vertebrate+Paleontology&rft.atitle=An+Avian+Egg+from+the+Lower+Cretaceous+%28Albian%29+Liangtoutang+Formation+of+Zhejiang+Province%2C+China&rft.volume=36&rft.issue=3&rft.pages=e1100631&rft.date=2016&rft_id=info%3Adoi%2F10.1080%2F02724634.2016.1100631&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A88169746%23id-name%3DS2CID&rft.aulast=Lawver&rft.aufirst=Daniel+R.&rft.au=Jin%2C+Xingsheng&rft.au=Jackson%2C+Frankie+D.&rft.au=Wang%2C+Qiongying&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-38">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=67196">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=basicTaxonInfo&taxon_no=68519">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-Xie_et_al_2016-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-Xie_et_al_2016_40-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFXieZhangJinLi2016" class="citation journal cs1">Xie, J.-F.; Zhang, S.-K.; Jin, X.-S.; Li, D.-Q.; Zhou, L.-Q. (2016). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160129003559/http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201512/P020151203499501638411.pdf">"A new type of dinosaur eggs from Early Cretaceous of Gansu Province, China"</a> <span class="cs1-format">(PDF)</span>. <i>Vertebrata PalAsiatica</i>. <b>54</b> (1): 1–10. Archived from <a rel="nofollow" class="external text" href="http://www.ivpp.ac.cn/cbw/gjzdwxb/pressonline/201512/P020151203499501638411.pdf">the original</a> <span class="cs1-format">(PDF)</span> on January 29, 2016<span class="reference-accessdate">. Retrieved <span class="nowrap">January 11,</span> 2016</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Vertebrata+PalAsiatica&rft.atitle=A+new+type+of+dinosaur+eggs+from+Early+Cretaceous+of+Gansu+Province%2C+China&rft.volume=54&rft.issue=1&rft.pages=1-10&rft.date=2016&rft.aulast=Xie&rft.aufirst=J.-F.&rft.au=Zhang%2C+S.-K.&rft.au=Jin%2C+X.-S.&rft.au=Li%2C+D.-Q.&rft.au=Zhou%2C+L.-Q.&rft_id=http%3A%2F%2Fwww.ivpp.ac.cn%2Fcbw%2Fgjzdwxb%2Fpressonline%2F201512%2FP020151203499501638411.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=65562">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-The_Palaeobiology_Database-42"><span class="mw-cite-backlink">^ <a href="#cite_ref-The_Palaeobiology_Database_42-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-The_Palaeobiology_Database_42-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=84312">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-43">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67195">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-44"><span class="mw-cite-backlink"><b><a href="#cite_ref-44">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=67290">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-45"><span class="mw-cite-backlink"><b><a href="#cite_ref-45">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.paleodb.org/cgi-bin/bridge.pl?action=checkTaxonInfo&taxon_no=81708">The Palaeobiology Database</a></span>
</li>
<li id="cite_note-46"><span class="mw-cite-backlink"><b><a href="#cite_ref-46">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFNorellClarkDashzevegBarsbold1994" class="citation journal cs1">Norell, M. A.; Clark, J. M.; Dashzeveg, D.; Barsbold, T.; Chiappe, L. M.; Davidson, A. R.; McKenna, M. C.; Novacek, M. J. (1994). "A theropod dinosaur embryo, and the affinities of the Flaming Cliffs Dinosaur eggs". <i>Science</i>. <b>266</b> (5186): 779–782. <a href="/enwiki/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1994Sci...266..779N">1994Sci...266..779N</a>. <a href="/enwiki/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1126%2Fscience.266.5186.779">10.1126/science.266.5186.779</a>. <a href="/enwiki/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//pubmed.ncbi.nlm.nih.gov/17730398">17730398</a>. <a href="/enwiki/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:22333224">22333224</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Science&rft.atitle=A+theropod+dinosaur+embryo%2C+and+the+affinities+of+the+Flaming+Cliffs+Dinosaur+eggs&rft.volume=266&rft.issue=5186&rft.pages=779-782&rft.date=1994&rft_id=info%3Adoi%2F10.1126%2Fscience.266.5186.779&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A22333224%23id-name%3DS2CID&rft_id=info%3Apmid%2F17730398&rft_id=info%3Abibcode%2F1994Sci...266..779N&rft.aulast=Norell&rft.aufirst=M.+A.&rft.au=Clark%2C+J.+M.&rft.au=Dashzeveg%2C+D.&rft.au=Barsbold%2C+T.&rft.au=Chiappe%2C+L.+M.&rft.au=Davidson%2C+A.+R.&rft.au=McKenna%2C+M.+C.&rft.au=Novacek%2C+M.+J.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></span>
</li>
<li id="cite_note-mateus-et-al-47"><span class="mw-cite-backlink"><b><a href="#cite_ref-mateus-et-al_47-0">^</a></b></span> <span class="reference-text">Mateus et al. (1998).</span>
</li>
<li id="cite_note-dericqles-et-al-48"><span class="mw-cite-backlink"><b><a href="#cite_ref-dericqles-et-al_48-0">^</a></b></span> <span class="reference-text">de Ricqles et al. (2001).</span>
</li>
<li id="cite_note-reisz-et-al-49"><span class="mw-cite-backlink"><b><a href="#cite_ref-reisz-et-al_49-0">^</a></b></span> <span class="reference-text">"Abstract," Reisz et al. (2005); page 761.</span>
</li>
<li id="cite_note-horner-weishampel-50"><span class="mw-cite-backlink"><b><a href="#cite_ref-horner-weishampel_50-0">^</a></b></span> <span class="reference-text">"Correction: A comparative embryological study of two ornithischian dinosaurs," Horner and Weishampel (1996); page 103.</span>
</li>
<li id="cite_note-enbd-fossilize-112-51"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-fossilize-112_51-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-fossilize-112_51-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"How to Fossilize an Egg," Carpenter (1999); page 112.</span>
</li>
<li id="cite_note-enbd-fossilize-113-52"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-fossilize-113_52-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-fossilize-113_52-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-enbd-fossilize-113_52-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">"How to Fossilize an Egg," Carpenter (1999); page 113.</span>
</li>
<li id="cite_note-enbd-fossilize-108-53"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-fossilize-108_53-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-fossilize-108_53-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"How to Fossilize an Egg," Carpenter (1999); page 108.</span>
</li>
<li id="cite_note-enbd-fossilize-114-54"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-fossilize-114_54-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-fossilize-114_54-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"How to Fossilize an Egg," Carpenter (1999); page 114.</span>
</li>
<li id="cite_note-enbd-fossilize-114-115-55"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-fossilize-114-115_55-0">^</a></b></span> <span class="reference-text">"How to Fossilize an Egg," Carpenter (1999); pages 114–115.</span>
</li>
<li id="cite_note-enbd-fossilize-115-56"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-fossilize-115_56-0">^</a></b></span> <span class="reference-text">"How to Fossilize an Egg," Carpenter (1999); page 115.</span>
</li>
<li id="cite_note-enbd-fossilize-111-57"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-fossilize-111_57-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-fossilize-111_57-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"How to Fossilize an Egg," Carpenter (1999); page 111.</span>
</li>
<li id="cite_note-enbd-fossilize-110-58"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-fossilize-110_58-0">^</a></b></span> <span class="reference-text">"How to Fossilize an Egg," Carpenter (1999); page 110.</span>
</li>
<li id="cite_note-enbd-collecting-117-59"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-collecting-117_59-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-collecting-117_59-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-enbd-collecting-117_59-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">"Collecting Eggs," Carpenter (1999); page 117.</span>
</li>
<li id="cite_note-enbd-collecting-117-118-60"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-collecting-117-118_60-0">^</a></b></span> <span class="reference-text">"Collecting Eggs," Carpenter (1999); pages 117–118.</span>
</li>
<li id="cite_note-enbd-collecting-118-61"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-collecting-118_61-0">^</a></b></span> <span class="reference-text">"Collecting Eggs," Carpenter (1999); page 118.</span>
</li>
<li id="cite_note-enbd-tools-128-62"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-tools-128_62-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-tools-128_62-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-enbd-tools-128_62-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-enbd-tools-128_62-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-enbd-tools-128_62-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); page 128.</span>
</li>
<li id="cite_note-enbd-tools-130-63"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-tools-130_63-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-tools-130_63-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-enbd-tools-130_63-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-enbd-tools-130_63-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); page 130.</span>
</li>
<li id="cite_note-64"><span class="mw-cite-backlink"><b><a href="#cite_ref-64">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external free" href="https://embryo.asu.edu/pages/acid-dissolution-fossil-dinosaur-eggs">https://embryo.asu.edu/pages/acid-dissolution-fossil-dinosaur-eggs</a> Last paragraph</span>
</li>
<li id="cite_note-enbd-tools-128-130-65"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-tools-128-130_65-0">^</a></b></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); pages 128–130.</span>
</li>
<li id="cite_note-enbd-collecting-7-11-66"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-collecting-7-11_66-0">^</a></b></span> <span class="reference-text">"Fig 7.11," Carpenter (1999); page 118.</span>
</li>
<li id="cite_note-enbd-tools-133-67"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-tools-133_67-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-tools-133_67-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-enbd-tools-133_67-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-enbd-tools-133_67-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); page 133.</span>
</li>
<li id="cite_note-enbd-tools-134-68"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-tools-134_68-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-tools-134_68-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); page 134.</span>
</li>
<li id="cite_note-enbd-tools-122-69"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-tools-122_69-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-tools-122_69-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); page 122.</span>
</li>
<li id="cite_note-enbd-tools-124-70"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-tools-124_70-0">^</a></b></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); page 124.</span>
</li>
<li id="cite_note-enbd-tools-125-71"><span class="mw-cite-backlink">^ <a href="#cite_ref-enbd-tools-125_71-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-enbd-tools-125_71-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); page 125.</span>
</li>
<li id="cite_note-enbd-tools-131-72"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-tools-131_72-0">^</a></b></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); page 131.</span>
</li>
<li id="cite_note-enbd-tools-132-73"><span class="mw-cite-backlink"><b><a href="#cite_ref-enbd-tools-132_73-0">^</a></b></span> <span class="reference-text">"Tools of the Trade," Carpenter (1999); page 132.</span>
</li>
</ol>
<span class="error mw-ext-cite-error" lang="en" dir="ltr">Cite error: A <a href="/enwiki/wiki/Help:Footnotes#WP:LDR" title="Help:Footnotes">list-defined reference</a> named "enbd-first-1" is not used in the content (see the <a href="/enwiki/wiki/Help:Cite_errors/Cite_error_references_missing_key" title="Help:Cite errors/Cite error references missing key">help page</a>).</span></div>
<h2><span class="mw-headline" id="References">References</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Dinosaur_egg&action=edit&section=25" title="Edit section: References">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<ul><li>Carpenter, Kenneth (1999). <i>Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Life of the Past)</i>, Indiana University Press; <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><a href="/enwiki/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/0-253-33497-7" title="Special:BookSources/0-253-33497-7">0-253-33497-7</a>.</li>
<li>Deeming, D. C. and M. W. J. Ferguson (eds.) 1991. Egg incubation: its effect on embryonic development in birds and reptiles. Cambridge University Press, UK. 448pp.</li>
<li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFGlut2003" class="citation cs2">Glut, Donald F. (2003), <a rel="nofollow" class="external text" href="https://archive.org/details/dinosaursencyclo00glut_2/page/613">"Appendix: Dinosaur Tracks and Eggs"</a>, <i>Dinosaurs: The Encyclopedia. 3rd Supplement</i>, Jefferson, North Carolina: McFarland & Company, Inc., pp. <a rel="nofollow" class="external text" href="https://archive.org/details/dinosaursencyclo00glut_2/page/613">613–652</a>, <a href="/enwiki/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0-7864-1166-5" title="Special:BookSources/978-0-7864-1166-5"><bdi>978-0-7864-1166-5</bdi></a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Appendix%3A+Dinosaur+Tracks+and+Eggs&rft.btitle=Dinosaurs%3A+The+Encyclopedia.+3rd+Supplement&rft.place=Jefferson%2C+North+Carolina&rft.pages=613-652&rft.pub=McFarland+%26+Company%2C+Inc.&rft.date=2003&rft.isbn=978-0-7864-1166-5&rft.aulast=Glut&rft.aufirst=Donald+F.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fdinosaursencyclo00glut_2%2Fpage%2F613&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></li>
<li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFHornerWeishampel1996" class="citation journal cs1">Horner, John R.; Weishampel, David B. (1996). <a rel="nofollow" class="external text" href="https://doi.org/10.1038%2F383103b0">"A comparative embryological study of two ornithischian dinosaurs - a correction"</a>. <i>Nature</i>. <b>383</b> (6595): 256–257. <a href="/enwiki/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1996Natur.383..103H">1996Natur.383..103H</a>. <a href="/enwiki/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="cs1-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1038%2F383103b0">10.1038/383103b0</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Nature&rft.atitle=A+comparative+embryological+study+of+two+ornithischian+dinosaurs+-+a+correction&rft.volume=383&rft.issue=6595&rft.pages=256-257&rft.date=1996&rft_id=info%3Adoi%2F10.1038%2F383103b0&rft_id=info%3Abibcode%2F1996Natur.383..103H&rft.aulast=Horner&rft.aufirst=John+R.&rft.au=Weishampel%2C+David+B.&rft_id=%2F%2Fdoi.org%2F10.1038%252F383103b0&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></li>
<li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFMateusMateusAntunesMateus1998" class="citation journal cs1">Mateus, I; Mateus, H; Antunes, MT; Mateus, O; Taquet, P; Ribeiro, V; Manuppella, G (1998). "Upper Jurassic theropod dinosaur embryos from Lourinhã (Portugal)". <i>Memórias da Academia das Ciências de Lisboa</i>. <b>37</b>: 101–110.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Mem%C3%B3rias+da+Academia+das+Ci%C3%AAncias+de+Lisboa&rft.atitle=Upper+Jurassic+theropod+dinosaur+embryos+from+Lourinh%C3%A3+%28Portugal%29&rft.volume=37&rft.pages=101-110&rft.date=1998&rft.aulast=Mateus&rft.aufirst=I&rft.au=Mateus%2C+H&rft.au=Antunes%2C+MT&rft.au=Mateus%2C+O&rft.au=Taquet%2C+P&rft.au=Ribeiro%2C+V&rft.au=Manuppella%2C+G&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></li>
<li>Moskvitch, Katia. <a rel="nofollow" class="external text" href="https://www.bbc.co.uk/news/science-environment-11734616">"Eggs with the Oldest Known Embryos of a Dinosaur Found"</a>. BBC News. November 12, 2010.</li>
<li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFde_RicqlèsMateusAntunesTaquet2001" class="citation journal cs1">de Ricqlès, A.; Mateus, O.; Antunes, M. T.; Taquet, P. (2001). "Histomorphogenesis of embryos of Upper Jurassic theropods from Lourinhã (Portugal)". <i>Comptes Rendus de l'Académie des Sciences, Série IIA</i>. <b>332</b> (10): 647–656. <a href="/enwiki/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2001CRASE.332..647D">2001CRASE.332..647D</a>. <a href="/enwiki/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fs1251-8050%2801%2901580-4">10.1016/s1251-8050(01)01580-4</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Comptes+Rendus+de+l%27Acad%C3%A9mie+des+Sciences%2C+S%C3%A9rie+IIA&rft.atitle=Histomorphogenesis+of+embryos+of+Upper+Jurassic+theropods+from+Lourinh%C3%A3+%28Portugal%29&rft.volume=332&rft.issue=10&rft.pages=647-656&rft.date=2001&rft_id=info%3Adoi%2F10.1016%2Fs1251-8050%2801%2901580-4&rft_id=info%3Abibcode%2F2001CRASE.332..647D&rft.aulast=de+Ricql%C3%A8s&rft.aufirst=A.&rft.au=Mateus%2C+O.&rft.au=Antunes%2C+M.+T.&rft.au=Taquet%2C+P.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></li>
<li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite id="CITEREFReiszScottSuesEvans2005" class="citation journal cs1">Reisz, Robert R.; Scott, Diane; Sues, Hans-Dieter; Evans, David C.; Raath, Michael A. (2005). <a rel="nofollow" class="external text" href="http://doc.rero.ch/record/14975/files/PAL_E2124.pdf">"Embryos of an Early Jurassic prosauropod dinosaur and their evolutionary significance"</a> <span class="cs1-format">(PDF)</span>. <i>Science</i>. <b>309</b> (5735): 761–764. <a href="/enwiki/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2005Sci...309..761R">2005Sci...309..761R</a>. <a href="/enwiki/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1126%2Fscience.1114942">10.1126/science.1114942</a>. <a href="/enwiki/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//pubmed.ncbi.nlm.nih.gov/16051793">16051793</a>. <a href="/enwiki/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:37548361">37548361</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Science&rft.atitle=Embryos+of+an+Early+Jurassic+prosauropod+dinosaur+and+their+evolutionary+significance&rft.volume=309&rft.issue=5735&rft.pages=761-764&rft.date=2005&rft_id=info%3Adoi%2F10.1126%2Fscience.1114942&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A37548361%23id-name%3DS2CID&rft_id=info%3Apmid%2F16051793&rft_id=info%3Abibcode%2F2005Sci...309..761R&rft.aulast=Reisz&rft.aufirst=Robert+R.&rft.au=Scott%2C+Diane&rft.au=Sues%2C+Hans-Dieter&rft.au=Evans%2C+David+C.&rft.au=Raath%2C+Michael+A.&rft_id=http%3A%2F%2Fdoc.rero.ch%2Frecord%2F14975%2Ffiles%2FPAL_E2124.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></li>
<li>Skinner, Justin.<a rel="nofollow" class="external text" href="http://www.insidetoronto.com/news/local/article/812684--rom-puts-oldest-dinosaur-eggs-ever-discovered-on-display">"ROM Puts Oldest Dinosaur Eggs Ever Discovered on Display"</a>. insidetoronto.com. May 6, 2010.</li>
<li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1133582631"/><cite class="citation cs2"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20140201213751/http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html">"What are dinosaur eggs?"</a>, <i>University of Bristol Earth Sciences</i>, archived from <a rel="nofollow" class="external text" href="http://palaeo.gly.bris.ac.uk/palaeofiles/eggs/default.html">the original</a> on February 1, 2014<span class="reference-accessdate">, retrieved <span class="nowrap">June 20,</span> 2013</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=University+of+Bristol+Earth+Sciences&rft.atitle=What+are+dinosaur+eggs%3F&rft_id=http%3A%2F%2Fpalaeo.gly.bris.ac.uk%2Fpalaeofiles%2Feggs%2Fdefault.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADinosaur+egg" class="Z3988"></span></li></ul>
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.navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}</style></div><div role="navigation" class="navbox" aria-labelledby="Eggs" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"/><style data-mw-deduplicate="TemplateStyles:r1063604349">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/enwiki/wiki/Template:Eggs" title="Template:Eggs"><abbr title="View this template" style=";;background:none transparent;border:none;box-shadow:none;padding:0;">v</abbr></a></li><li class="nv-talk"><a href="/enwiki/wiki/Template_talk:Eggs" title="Template talk:Eggs"><abbr title="Discuss this template" style=";;background:none transparent;border:none;box-shadow:none;padding:0;">t</abbr></a></li><li class="nv-edit"><a class="external text" href="https://en.wikipedia.org/enwiki/w/index.php?title=Template:Eggs&action=edit"><abbr title="Edit this template" style=";;background:none transparent;border:none;box-shadow:none;padding:0;">e</abbr></a></li></ul></div><div id="Eggs" style="font-size:114%;margin:0 4em"><a href="/enwiki/wiki/Egg" title="Egg">Eggs</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div id="List_of_egg_topics"><a href="/enwiki/wiki/List_of_egg_topics" title="List of egg topics">List of egg topics</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Types</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="/enwiki/wiki/Bird_egg" title="Bird egg">Bird</a></li>
<li><a href="/enwiki/wiki/Egg#Fish_and_amphibian_eggs" title="Egg">Fish and amphibian</a></li>
<li><a href="/enwiki/wiki/Monotreme" title="Monotreme">Monotreme</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Egg_fossil" title="Egg fossil">Fossil record</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="/enwiki/wiki/Cephalopod_egg_fossil" title="Cephalopod egg fossil">Cephalopod</a></li>
<li><a href="/enwiki/wiki/Fish_egg_fossil" title="Fish egg fossil">Fish</a></li>
<li><a href="/enwiki/wiki/Reptile_egg_fossil" title="Reptile egg fossil">Reptile</a> (<a class="mw-selflink selflink">dinosaur</a>)</li>
<li><a href="/enwiki/wiki/Egg_paleopathology" title="Egg paleopathology">Pathology</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Biology</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="/enwiki/wiki/Egg_allergy" title="Egg allergy">Allergy</a></li>
<li><a href="/enwiki/wiki/Egg_cell" title="Egg cell">Egg cell</a></li>
<li><a href="/enwiki/wiki/Embryo" title="Embryo">Embryo</a></li>
<li><a href="/enwiki/wiki/Ichthyoplankton" title="Ichthyoplankton">Ichthyoplankton</a></li>
<li><a href="/enwiki/wiki/Oogamy" title="Oogamy">Oogamy</a></li>
<li><a href="/enwiki/wiki/Oogenesis" title="Oogenesis">Oogenesis</a></li>
<li><a href="/enwiki/wiki/Ootheca" title="Ootheca">Ootheca</a></li>
<li><a href="/enwiki/wiki/Ovary" title="Ovary">Ovary</a></li>
<li><a href="/enwiki/wiki/Oviduct" title="Oviduct">Oviduct</a></li>
<li><a href="/enwiki/wiki/Oviparity" title="Oviparity">Oviparity</a></li>
<li><a href="/enwiki/wiki/Ovoviviparity" title="Ovoviviparity">Ovoviviparity</a></li>
<li><a href="/enwiki/wiki/Ovulation" title="Ovulation">Ovulation</a></li>
<li><a href="/enwiki/wiki/Spawn_(biology)" title="Spawn (biology)">Spawn</a></li>
<li><a href="/enwiki/wiki/Egg_tooth" title="Egg tooth">Tooth</a></li>
<li><a href="/enwiki/wiki/Trophic_egg" title="Trophic egg">Trophic</a></li>
<li><a href="/enwiki/wiki/Zygote" title="Zygote">Zygote</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Components</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="/enwiki/wiki/Yolk" title="Yolk">Yolk</a></li>
<li><a href="/enwiki/wiki/Egg_white" title="Egg white">White</a></li>
<li><a href="/enwiki/wiki/Eggshell" title="Eggshell">Shell</a> and <a href="/enwiki/wiki/Eggshell_membrane" title="Eggshell membrane">membrane</a></li>
<li><a href="/enwiki/wiki/Chalaza" title="Chalaza">Chalaza</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Egg_as_food" title="Egg as food">As food</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="/enwiki/wiki/List_of_egg_dishes" title="List of egg dishes">List of egg dishes</a></li>
<li><a href="/enwiki/wiki/Balut_(food)" title="Balut (food)">Balut</a></li>
<li><a href="/enwiki/wiki/Eggs_Benedict" title="Eggs Benedict">Benedict</a></li>
<li><a href="/enwiki/wiki/Boiled_egg" title="Boiled egg">Boiled</a></li>
<li><a href="/enwiki/wiki/Century_egg" title="Century egg">Century</a></li>
<li><a href="/enwiki/wiki/Coddled_egg" title="Coddled egg">Coddled</a></li>
<li><a href="/enwiki/wiki/List_of_custard_desserts" title="List of custard desserts">Custard desserts</a></li>
<li><a href="/enwiki/wiki/Deviled_egg" title="Deviled egg">Deviled</a></li>
<li><a href="/enwiki/wiki/Eggnog" title="Eggnog">Eggnog</a></li>
<li><a href="/enwiki/wiki/Fried_egg" title="Fried egg">Fried</a></li>
<li><a href="/enwiki/wiki/Iron_egg" title="Iron egg">Iron</a></li>
<li><a href="/enwiki/wiki/Meringue" title="Meringue">Meringue</a></li>
<li><a href="/enwiki/wiki/Omelette" title="Omelette">Omelette</a></li>
<li><a href="/enwiki/wiki/Onsen_tamago" title="Onsen tamago">Onsen tamago</a></li>
<li><a href="/enwiki/wiki/Poached_egg" title="Poached egg">Poached</a></li>
<li><a href="/enwiki/wiki/Powdered_egg" class="mw-redirect" title="Powdered egg">Powdered</a></li>
<li><a href="/enwiki/wiki/Pickled_egg" title="Pickled egg">Pickled</a></li>
<li><a href="/enwiki/wiki/Roe" title="Roe">Roe</a></li>
<li><a href="/enwiki/wiki/Scotch_egg" title="Scotch egg">Scotch</a></li>
<li><a href="/enwiki/wiki/Scrambled_eggs" title="Scrambled eggs">Scrambled</a></li>
<li><a href="/enwiki/wiki/Shirred_eggs" title="Shirred eggs">Shirred</a></li>
<li><a href="/enwiki/wiki/Smoked_egg" title="Smoked egg">Smoked</a></li>
<li><a href="/enwiki/wiki/Souffl%C3%A9" title="Soufflé">Soufflé</a></li>
<li><a href="/enwiki/wiki/Tea_egg" title="Tea egg">Tea</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Category:Eggs_in_culture" title="Category:Eggs in culture">In culture</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="/enwiki/wiki/Egg_balancing" title="Egg balancing">Balancing</a></li>
<li><a href="/enwiki/wiki/Egg_carton" title="Egg carton">Carton</a></li>
<li><a href="/enwiki/wiki/Egg_decorating" title="Egg decorating">Decorating</a></li>
<li><a href="/enwiki/wiki/Easter_egg" title="Easter egg">Easter egg</a></li>
<li><a href="/enwiki/wiki/Egg-and-spoon_race" title="Egg-and-spoon race">Egg-and-spoon race</a></li>
<li><a href="/enwiki/wiki/Egg_drop_competition" title="Egg drop competition">Egg drop competition</a></li>
<li><a href="/enwiki/wiki/Egging" title="Egging">Egging</a></li>
<li><a href="/enwiki/wiki/Faberg%C3%A9_egg" title="Fabergé egg">Fabergé egg</a></li>
<li><a href="/enwiki/wiki/Free-range_egg" class="mw-redirect" title="Free-range egg">Free range</a></li>
<li><a href="/enwiki/wiki/Humpty_Dumpty" title="Humpty Dumpty">Humpty Dumpty</a></li>
<li><a href="/enwiki/wiki/Egg_hunt" title="Egg hunt">Hunt</a></li>
<li><a href="/enwiki/wiki/Oology" title="Oology">Oology</a></li>
<li><a href="/enwiki/wiki/Oomancy" title="Oomancy">Oomancy</a></li>
<li><a href="/enwiki/wiki/Organic_egg_production" title="Organic egg production">Organic</a></li>
<li><a href="/enwiki/wiki/Category:Egg_organizations" title="Category:Egg organizations">Organizations</a></li>
<li><a href="/enwiki/wiki/Ovo_vegetarianism" title="Ovo vegetarianism">Ovo vegetarianism</a></li>
<li><a href="/enwiki/wiki/Pysanka" class="mw-redirect" title="Pysanka">Pysanka</a>
<ul><li><a href="/enwiki/wiki/Vegreville_egg" title="Vegreville egg">Vegreville egg</a></li></ul></li>
<li><a href="/enwiki/wiki/Egg_rolling" title="Egg rolling">Rolling</a></li>
<li><a href="/enwiki/wiki/Egg_tapping" title="Egg tapping">Tapping</a></li>
<li><a href="/enwiki/wiki/Egg_tossing" title="Egg tossing">Tossing</a></li></ul>
</div></td></tr><tr><td class="navbox-abovebelow hlist" colspan="2"><div>
<ul><li><img alt="" src="/upwiki/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" title="Category" width="16" height="16" class="noviewer" srcset="/upwiki/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, /upwiki/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /> <b><a href="/enwiki/wiki/Category:Eggs" title="Category:Eggs">Category</a></b></li>
<li><img alt="" src="/upwiki/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" title="Commons page" width="12" height="16" class="noviewer" srcset="/upwiki/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png 1.5x, /upwiki/wikipedia/en/thumb/4/4a/Commons-logo.svg/24px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /> <b><a href="https://commons.wikimedia.org/wiki/Category:Eggs" class="extiw" title="commons:Category:Eggs">Commons</a></b></li></ul>
</div></td></tr></tbody></table></div>
<div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"/><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1061467846"/></div><div role="navigation" class="navbox authority-control" aria-label="Navbox" style="padding:3px"><table class="nowraplinks hlist navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Help:Authority_control" title="Help:Authority control">Authority control</a>: National libraries <a href="https://www.wikidata.org/wiki/Q3817122#identifiers" title="Edit this at Wikidata"><img alt="Edit this at Wikidata" src="/upwiki/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/10px-OOjs_UI_icon_edit-ltr-progressive.svg.png" decoding="async" width="10" height="10" style="vertical-align: text-top" class="noprint" srcset="/upwiki/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/15px-OOjs_UI_icon_edit-ltr-progressive.svg.png 1.5x, /upwiki/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png 2x" data-file-width="20" data-file-height="20" /></a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><span class="uid"><a rel="nofollow" class="external text" href="http://uli.nli.org.il/F/?func=find-b&local_base=NLX10&find_code=UID&request=987007563411805171">Israel</a></span></li>
<li><span class="uid"><a rel="nofollow" class="external text" href="https://id.loc.gov/authorities/subjects/sh93004279">United States</a></span></li></ul>
</div></td></tr></tbody></table></div></div>' |
Whether or not the change was made through a Tor exit node (tor_exit_node) | false |
Unix timestamp of change (timestamp) | '1675703763' |