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{{Short description|Genus of dinosaur from the Early Cretaceous}}
{{italictitle}}{{Taxobox
{{Use American English|date=September 2020}}
| name = ''Utahraptor''
{{Use mdy dates|date=January 2021}}
| fossil_range = [[Early Cretaceous]], {{Fossil range|126}}
{{Automatic taxobox
| image = Utahraptor BW.jpg
| fossil_range = [[Early Cretaceous]] ([[Berriasian]] – [[Valanginian]]), {{Fossil range|139|134.6}}
| image_caption = Artist's reconstruction
| image = BYU Utahraptor skeletal mount.jpg
| regnum = [[Animal]]ia
| image_caption = Reconstructed skeleton in [[BYU Museum of Paleontology]]
| phylum = [[Chordate|Chordata]]
| taxon = Utahraptor
| classis = [[Reptile|Reptilia]]
| authority = [[James I. Kirkland|Kirkland]], Gaston & Burge, 1993
| superordo = [[Dinosaur]]ia
| type_species = {{extinct}}'''''Utahraptor ostrommaysi'''''
| ordo = [[Saurischia]]
| type_species_authority = Kirkland ''et al.'', 1993
| subordo = [[Theropoda]]
| familia = [[Dromaeosauridae]]
| subfamilia = [[Dromaeosaurinae]]
| genus = '''''Utahraptor'''''
| genus_authority = [[James Kirkland (paleontologist)|Kirkland]], [[Robert Gaston|Gaston]] & [[Donald L. Burge|Burge]], 1993
| subdivision_ranks = [[Species]]
| subdivision =
'''''U. ostrommaysorum''''' <small>Kirkland, Gaston, & Burge, 1993 ([[Type species|type]])</small>
}}
}}

'''''Utahraptor''''' (meaning "[[Utah]]'s predator")<ref name="Kirkland93"/> is the largest known member of the [[theropod]] [[dinosaur]] family [[Dromaeosauridae]], and dates from the upper [[Barremian]] [[faunal stage|stage]] of the early [[Cretaceous]] period (about 126 million years ago).<ref name="Kirkland93"/>
'''''Utahraptor''''' (meaning "[[Utah]]'s predator"<!-- 'Utah's predator' is correct!! 'Raptor' normally translates to 'seizer' or 'thief' in other dromaeosaur descriptions. However, Kirkland (1993, Page 5) actually calls it 'Utah's predator' in the etymology. -->) is a [[genus]] of large [[dromaeosaurid]] (a group of feathered carnivorous [[theropod]]s) [[dinosaur]] that lived during the [[Early Cretaceous]] [[Geological period|period]] from around 135 to 130 million years ago in what is now the [[United States]]. The genus was described in 1993 by American [[paleontologist]] [[James I. Kirkland|James Kirkland]] and colleagues with the [[type species]] '''''Utahraptor ostrommaysi''''', based on fossils that had been unearthed earlier from the [[Cedar Mountain Formation]] of [[Utah]]. Later, many additional specimens were described including those from the [[skull]] and postcranium in addition to those of younger individuals.

The genus contains a single species, '''''Utahraptor ostrommaysi'''''. It is the largest-known member of the family [[Dromaeosauridae]], measuring about {{convert|6|-|7|m|ft}} long and typically weighing less than {{convert|500|kg|lb}}. As a heavily built, ground-dwelling, [[bipedal]] [[carnivore]], its large size and variety of unique features have earned it attention in both [[pop culture]] and the scientific community. The jaws of ''Utahraptor'' were lined with small, serrated [[teeth]] that were used in conjunction with a large "killing claw" on its second toe to dispatch its prey. Its skull was boxy and elongated, akin to other dromaeosaurids like ''[[Dromaeosaurus]]'' and ''[[Velociraptor]]''.

Being a carnivore, ''Utahraptor'' was adapted to hunt the other animals of the Cedar Mountain Formation ecosystem such as [[ankylosaur]]s and [[iguanodont]]s. Evidence from the leg physiology supports the idea of ''Utahraptor'' being an [[ambush predator]], in contrast to other dromaeosaurs that were [[pursuit predator]]s.

==Discovery and naming==
[[File:Utahraptor premaxilla BYU.jpg|thumb|left|Premaxilla of BYU 7510 14585]]
The first specimens of ''Utahraptor'' were found in 1975 by [[James A. Jensen|Jim Jensen]] in the Dalton Wells Quarry of Utah, near the town of [[Moab, Utah|Moab]], but did not receive much attention. After a find of a large claw by Carl Limone in October 1991, [[James I. Kirkland|James Kirkland]], Robert Gaston and Donald Burge uncovered further remains of ''Utahraptor'' in 1991 in the Gaston Quarry in [[Grand County, Utah|Grand County]], [[Utah]], within the Yellow Cat and Poison Strip members of the [[Cedar Mountain Formation]]. The [[holotype]] of ''Utahraptor'', CEUM 184v.86, consists of a second pedal [[ungual]], with potentially assigned elements from other specimens: pedal ungual CEUM 184v.294, [[tibia]] CEUM 184v.260 and [[premaxilla]] CEUM 184v.400.<ref name="Kirkland93">{{Cite journal |last1=Kirkland |first1=J. I. |author-link=James I. Kirkland |last2=Burge |first2=D. |last3=Gaston |first3=R. |year=1993 |title=A large dromaeosaurid (Theropoda) from the Lower Cretaceous of Eastern Utah |url=https://www.academia.edu/225747 |journal=Hunteria |volume=2 |issue=10 |pages=1–16}}</ref> The holotype is housed in the paleontology collections of the [[USU Eastern Prehistoric Museum|Prehistoric Museum at Utah State University Eastern]]. [[Brigham Young University]], the depository of Jensen's finds, currently houses the largest collection of ''Utahraptor'' fossils. [https://eastern.usu.edu/prehistoric-museum/exhibits/paleontology/utahraptor]

The [[Type (biology)|type]] species, ''Utahraptor ostrommaysi'', was named by Kirkland, Gaston and Burge in June 1993. The [[genus]] name ''Utahraptor'' is in reference to [[Utah]], where the remains were found. The [[Specific name (zoology)|specific name]], ''ostrommaysi'', is in honor to [[John Ostrom]] for his investigations on ''[[Deinonychus]]'' and its relationships to [[bird]]s, as well as Chris Mays, who helped in the research of ''Utahraptor'' by founding [[Dinamation]].<ref name="Kirkland93"/> From his description, Kirkland stated the meaning of genus name to be "Utah's predator,"<ref name="Kirkland93"/> but the Latin word ''raptor'' translates to 'robber' or 'plunderer', not 'predator'.<ref>{{cite web|title=raptŏr - ONLINE LATIN DICTIONARY|website=Online Latin Dictionary|url=https://www.online-latin-dictionary.com/latin-english-dictionary.php?lemma=RAPTOR200}}</ref> Earlier, it had been intended to name the species "''U. spielbergi''" after [[film director]] [[Steven Spielberg]], in exchange for him funding paleontological research, but no agreement could be reached on the amount of financial assistance.<ref>{{cite news |last=Adams |first=Brooke |date=June 15, 1993 |title=Director Loses Utahraptor Name Game |work=Deseret News |url=http://www.deseretnews.com/article/295496/DIRECTOR-LOSES-UTAHRAPTOR-NAME-GAME.html |archive-url=https://web.archive.org/web/20161023033111/http://www.deseretnews.com/article/295496/DIRECTOR-LOSES-UTAHRAPTOR-NAME-GAME.html |archive-date=October 23, 2016}}</ref>
[[File:Utahraptor ungual BYU.jpg|thumb|Pedal ungual II of CEUM 184v.294, housed at the Prehistoric Museum, USU Eastern.]]
In 2000, the specific name was emended by [[George Olshevsky]] to the plural genitive ''ostrommaysorum''.<ref>Olshevsky, G., 2000, ''An annotated checklist of dinosaur species by continent. Mesozoic Meanderings'' '''3''': 1-157</ref> However, Thiago Vernaschi V. Costa and Normand David in 2019 criticized the use of the species name ''U. ostrommaysorum'', since it has no clear justification or explanation. Although this spelling has been largely used by other authors, the genus ''Utahraptor'' was originally coined with the type species ''U. ostrommaysi'' and, given that the [[International Code of Zoological Nomenclature]] offers no provision for forming a [[genitive form]] from two persons with different names, Costa and David conclude that the original spelling ''ostrommaysi'' has to be regarded as an arbitrary combination of letters and not a correctly formed genitive form. Under this reasoning, ''ostrommaysorum'' has no valid use and the original spelling ''ostrommaysi'' does not need to be emended. Other alternative and also invalid spellings were used in scientific literature, such as ''ostromaysi'', ''ostromaysorum'', ''ostromayssorum'', ''ostromayorum'' and ''ostrommaysori''.<ref>{{cite journal|last1=Costa|first1=T. V. V.|last2=David|first2=N.|date=2019|title=Commentaries on different uses of the specific epithet of the large dromaeosaurid Utahraptor Kirkland et al., 1993 (Dinosauria, Theropoda)|url=https://www.biotaxa.org/bzn/article/view/50672|journal=The Bulletin of Zoological Nomenclature|volume=76|issue=1|pages=90−96|doi=10.21805/bzn.v76.a028|s2cid=166691677|url-access=subscription}}</ref>

Some elements were wrongly referred to the genus. The [[lacrimal bone]] of the specimen CEUM 184v.83 turned out to be a postorbital from the ankylosaur ''[[Gastonia (dinosaur)|Gastonia]]''. Britt ''et al.'' also suggested that the previously identified manual unguals of the specimens M184v.294, BYU 9438 and BYU 13068 are indeed pedal unguals.<ref>{{cite journal|last1=Britt|first1=B. B.|last2=Chure|first2=D. J.|last3=Stadtman|first3=K. L.|last4=Madsen|first4=J. H.|last5=Scheetz|first5=R. D.|last6=Burge|first6=D. L.|year=2001|title=New osteological data and the affinities of Utahraptor from the Cedar Mountain Fm. (Early Cretaceous) of Utah|journal=Journal of Vertebrate Paleontology|volume=21|issue=3|page=36A}}</ref> This suggestion was confirmed by Senter in 2007.<ref>{{cite journal|last1=Senter|first1=P.|year=2007|title=A method for distinguishing dromaeosaurid manual unguals from pedal "sickle claws"|journal=Bulletin of the Gunma Museum of Natural History|issue=11|pages=1–6|issn=1342-4092}}</ref>


==Description==
==Description==
{{Multiple image
[[File:Utahraptor scale.png|left|thumb|Size of largest described (green) and reported (gray) specimens compared to a human]]
| image1 = Utahraptor Restoration.png
The [[holotype]] of ''Utahraptor'' is fragmentary, consisting of skull fragments, a tibia, claws and some caudal (tail) [[vertebra]]. The few elements suggest an animal about twice the size of ''[[Deinonychus]]''.<ref name="Kirkland93"/> Like other dromaeosaurids, ''Utahraptor'' had a huge curved claw on the second toe; one is preserved at {{convert|22|cm|in|abbr=off}} in length and is thought to reach {{convert|24|cm|in|abbr=off}} restored. The largest described specimens are estimated to have reached up to {{convert|7|m|ft|abbr=on}} long and roughly {{convert|400|kg|lb|abbr=on}} in weight, equivalent to the [[Grizzly bear]] in size.<ref name="Kirkland93"/><ref name="Holtz2008">Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages'' [http://www.geol.umd.edu/~tholtz/dinoappendix/DinoappendixSummer2008.pdf Supplementary Information]</ref> Some undescribed specimens in the [[BYU]] collections may have reached up to {{convert|11|m|ft|abbr=on}} long, though these await more detailed study.<ref name=brittetal2001>Britt, Chure, Stadtman, Madsen, Scheetz and Burge, (2001). "New osteological data and the affinities of ''Utahraptor'' from the Cedar Mountain Fm. (Early Cretaceous) of Utah." ''Journal of Vertebrate Paleontology'', '''21'''(3): 36A.</ref>
| caption1 = Restoration
| align = right
| image2 = Utahraptor size.png
| caption2 = ''Utahraptor'' specimens compared in size to a 1.8-metre-tall (5.9 ft) human
| perrow = 1 / 1
}}
''Utahraptor'' was one of, if not the largest and heaviest of all dromaeosaurids, with the largest assigned specimen BYUVP 15465 having a femoral length of {{cvt|56.5|-|60|cm}}.<ref>{{cite journal|last1=Erickson|first1=G. M.|last2=Rauhut|first2=O. W. M.|last3=Zhou|first3=Z.|last4=Turner|first4=A. H.|last5=Inouye|first5=B. D.|last6=Hu|first6=D.|last7=Norell|first7=M. A.|year=2009|title=Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx|journal=PLOS ONE|volume=4|issue=10|page=e7390|doi=10.1371/journal.pone.0007390|pmid=19816582|pmc=2756958|bibcode=2009PLoSO...4.7390E|doi-access=free}}</ref><ref>{{Cite journal |last1=Sues |first1=Hans-Dieter |author-link=Hans-Dieter Sues |last2=Averianov |first2=Alexander |last3=Britt |first3=Brooks B. |date=2022-12-22 |title=A giant dromaeosaurid theropod from the Upper Cretaceous (Turonian) Bissekty Formation of Uzbekistan and the status of Ulughbegsaurus uzbekistanensis |url=https://www.cambridge.org/core/product/identifier/S0016756822000954/type/journal_article |journal=Geological Magazine |language=en |volume=160 |issue=2 |pages=355–360 |doi=10.1017/S0016756822000954 |issn=0016-7568}}</ref>

''Utahraptor'' is estimated to have reached {{convert|6|-|7|m|ft}} in length and somewhat less than {{cvt|500|kg}}, comparable in weight to a [[polar bear]].<ref name="Kirkland93"/><ref>{{cite book|last=Chiappe|first=Luis M.|year=2007|title=Glorified Dinosaurs: The Origin and Early Evolution of Birds|publisher=Wiley-Liss|page=32|isbn=9780471247234}}</ref><ref>{{cite journal |last1=Martin |first1=Damien |last2=Currie |first2=Philip J. |last3=Kundrát |first3=Martin |title=Variability of bone microstructure and growth lines in the evolution of troodontids and dromaeosaurids |journal=Acta Zoologica |date=2023 |volume=105 |issue=2 |pages=135–175 |doi=10.1111/azo.12467|s2cid=258655244 }}</ref> Some authors estimated that it weighed up to {{cvt|250|-|350|kg}}.<ref>{{cite journal |last1=Benson |first1=R. B. J. |last2=Hunt |first2=G. |last3=Carrano |first3=M.T. |last4= Campione |first4=N. |last5=Mannion |first5=P. |title=Cope's rule and the adaptive landscape of dinosaur body size evolution |journal= Palaeontology |date=2018 |volume=61 |issue=1 |pages=13–48 |doi= 10.1111/pala.12329 |bibcode=2018Palgy..61...13B |doi-access=free }}</ref><ref>{{Cite journal |last1=Benson |first1=Roger B. J. |last2=Campione |first2=Nicolás E. |last3=Carrano |first3=Matthew T. |last4=Mannion |first4=Philip D. |last5=Sullivan |first5=Corwin |last6=Upchurch |first6=Paul |last7=Evans |first7=David C. |date=2014-05-06 |title=Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage |journal=PLOS Biology |language=en |volume=12 |issue=5 |pages=e1001853 |doi=10.1371/journal.pbio.1001853 |issn=1545-7885 |pmc=4011683 |pmid=24802911 |doi-access=free }} [https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001853#s5 Supporting Information]</ref><ref>{{cite journal|last1=Turner|first1=A.H.|last2=Pol|first2=D.|last3=Clarke|first3=J.A.|last4=Erickson|first4=G.M.|last5=Norell|first5=M.A.|date=2007|title=A Basal Dromaeosaurid and Size Evolution Preceding Avian Flight|journal=Science|volume=317|issue=5843|pages=1378−1381|bibcode=2007Sci...317.1378T|doi=10.1126/science.1144066|pmid=17823350|doi-access=free|url=http://doc.rero.ch/record/15414/files/PAL_E2770.pdf}} [https://web.archive.org/web/20180722145857/http://science.sciencemag.org/content/suppl/2007/09/06/317.5843.1378.DC1/Turner.SOM.pdf Supporting Online Material]</ref> In 2024, the body mass of BYUVP 2536 and BYUVP 1833 were estimated around {{convert|391|and|481|kg}} respectively, though BYUVP 7510-18078 was estimated to have weighed {{convert|777|kg|lb}}.<ref name=Pintore2024>{{Cite journal|last1=Pintore |first1=R. |last2=Hutchinson |first2=J. R. |last3=Bishop |first3=P. J. |last4=Tsai |first4=H. P. |last5=Houssaye |first5=A. |year=2024 |title=The evolution of femoral morphology in giant non-avian theropod dinosaurs |journal=Paleobiology |volume=50 |issue=2 |pages=308–329 |doi=10.1017/pab.2024.6 |doi-access=free |pmid=38846629 |pmc=7616063 |bibcode=2024Pbio...50..308P }}</ref>

Although [[feathers]] have never been found in association with ''Utahraptor'' specimens, there is strong phylogenetic evidence suggesting that all dromaeosaurids had them. The feathered genus ''[[Microraptor]]'' is one of the oldest-known dromaeosaurids and is phylo&shy;genetically more primitive than ''Utahraptor''.<ref>{{cite journal |doi= 10.1038/nature01342 |last1= Xu |first1= X. |last2= Zhou |first2= Z. |last3= Wang |first3= X. |last4= Kuang |first4=X. |last5= Zhang |first5=F. |last6=Du |first6=X. |year= 2003 |title= Four-winged dinosaurs from China |journal= Nature |volume= 421 |issue= 6921 |pages= 335–340 |pmid= 12540892 |bibcode= 2003Natur.421..335X |s2cid= 1160118 |url= http://doc.rero.ch/record/15275/files/PAL_E2574.pdf }}</ref> Since ''Microraptor'' and other dromaeosaurids possessed feathers, it is reasonable to assume that this trait was present in all of Dromaeosauridae. Feathers were very unlikely to have evolved more than once, so assuming that any given dromaeosaurid, such as ''Utahraptor'', lacked feathers would require positive evidence that they did not have them.<ref>{{cite journal |last1= Prum |first1= R. |last2= Brush |first2= A.H. |year= 2002 |title= The evolutionary origin and diversification of feathers |journal= The Quarterly Review of Biology |pmid= 12365352 |volume= 77 |issue=3 |pages= 261–295 |doi= 10.1086/341993 |s2cid= 6344830 }}</ref> So far, there is nothing to suggest that feathers were lost in larger, more derived species of dromaeosaurs.<ref>{{cite journal |last1= Turner |first1= AH |last2= Makovicky |first2= PJ |last3= Norell |first3= MA |title= Feather quill knobs in the dinosaur Velociraptor |journal= Science |volume= 317 |issue= 5845 |pages= 1721 |year= 2007 |pmid= 17885130 |doi= 10.1126/science.1145076 |bibcode= 2007Sci...317.1721T |doi-access= free |url= http://doc.rero.ch/record/15467/files/PAL_E2854.pdf }}</ref> The presence of quill knobs in ''[[Dakotaraptor]]'' evidenced that even larger [[dromaeosaurids]] had feathers.<ref name="DePalma2015">{{cite journal |last1=DePalma |first1=Robert A. |last2=Burnham |first2=David A. |last3=Martin |first3=Larry D. |last4=Larson |first4=Peter L. |author-link4=Peter Larson |last5=Bakker |first5=Robert T. |author-link5=Robert T. Bakker |date=October 30, 2015 |title=The first giant raptor (Theropoda: Dromaeosauridae) from the Hell Creek Formation |journal=Paleontological Contributions |doi=10.17161/paleo.1808.18764 |doi-access=free |hdl=1808/18764|hdl-access=free }}</ref>
[[File:BYU Utahraptor skull.jpg|thumb|left|Reconstructed skull, BYU]]
According to Kirkland ''et al.'' in 1993, ''Utahraptor'' can be recognized by a few special [[autapomorphies]]. The [[claws]] on its hand are more specialized as cutting blades than in other dromaeosaurids. It has a [[lacrimal bone]] with distinctly parallel mesial and outer sides that gives it an elongate subrectangular appearance in top view and it has a base of the nasal opening on the premaxilla parallel to the premaxillary tooth row.<ref name="Kirkland93"/> In the revised diagnosis conducted by Turner ''et al.'' in 2012, ''Utahraptor'' differs from other dromaeosaurids in having an elongate nasal process of the [[premaxilla]], a distal end of [[metatarsal]] III that is smooth, not ginglymoid, an L-shaped [[quadratojugal]] without a posterior process, the presence of a well-developed notch between the lesser [[trochanter]] and greater trochanter, and dorsal vertebrae that lack pleurocoels.<ref>{{cite journal|last1=Turner|first1=A. H.|last2=Makovicky|first2=P. J.|last3=Norell|first3=M. A.|title=A Review of Dromaeosaurid Systematics and Paravian Phylogeny|doi=10.1206/748.1|journal=Bulletin of the American Museum of Natural History|volume=371|issue=371|pages=1–206|year=2012|hdl=2246/6352|s2cid=83572446|url=https://zenodo.org/record/5399588}}</ref> Like other dromaeosaurids, ''Utahraptor'' had a large curved claw on the second toe of each foot. The second pedal ungual is preserved with a {{cvt|22|cm}} outside curve length and is estimated to reach {{cvt|24|cm}} in restoration.<ref name="Kirkland93"/>

==Classification==
''Utahraptor'' is a member of the [[family (biology)|family]] [[Dromaeosauridae]], a [[cladistics|clade]] of [[Theropoda|theropod]] [[dinosaur]]s commonly known as "raptors". ''Utahraptor'' is the largest known genus in the family and belongs to the same clade of other notable dinosaurs such as ''[[Velociraptor]]'', ''[[Deinonychus]]'', or ''[[Dromaeosaurus]]''. It is classified in the subfamily [[Dromaeosaurinae]], which is found in the clade [[Eudromaeosauria]].<ref name="Kirkland93"/>

In 2015, ''Utahraptor'' was found to be closely related to the smaller ''[[Dromaeosaurus]]'' and the giant [[Mongolia]]n and North American dromaeosaurid genera ''[[Achillobator]]'' and ''[[Dakotaraptor]]'':<ref name=DePalma2015/>
[[File:Dromaeosaurs.png|right|thumb|upright=1.6|Size of ''Utahraptor'' (5) compared with other dromaeosaurs]]
{{clade| style=font-size:100%; line-height:100%
|label1=[[Eudromaeosauria]]
|1={{clade
|1=''[[Saurornitholestes]]''
|2={{clade
|1=''[[Velociraptor]]''
|label2=[[Dromaeosaurinae]]
|2={{clade
|1=''[[Deinonychus]]''
|2={{clade
|1=''[[Atrociraptor]]''
|2={{clade
|1=''[[Achillobator]]''
|2={{clade
|1='''''Utahraptor'''''
|2={{clade
|1=''[[Dakotaraptor]]''
|2=''[[Dromaeosaurus]]'' }} }} }} }} }} }} }} }}

The cladogram below is the result of a cladistic analysis conducted by Cau ''et al.'' in 2017.<ref>{{cite journal |last1=Cau |first1=Andrea |last2=Beyrand |first2=Vincent |last3=Voeten |first3=Dennis F. A. E. |last4=Fernandez |first4=Vincent |last5=Tafforeau |first5=Paul |last6=Stein |first6=Koen |last7=Barsbold |first7=Rinchen |last8=Tsogtbaatar |first8=Khishigjav |last9=Currie |first9=Philip J. |author-link9=Philip J. Currie |last10=Godefroit |first10=Pascal |date=December 6, 2017 |title=Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs |journal=Nature |volume=552 |issue=7685 |pages=395–399 |bibcode=2017Natur.552..395C |doi=10.1038/nature24679 |pmid=29211712 |s2cid=4471941}}</ref>

{{clade| style=font-size:100%; line-height:100%;
|label1=[[Eudromaeosauria]]
|1={{Clade
|1=''[[Bambiraptor]]''
|2={{Clade
|1=''[[Tianyuraptor]]''
|2={{Clade
|label1=[[Dromaeosaurinae]]
|1={{Clade
|1=''[[Achillobator]]''
|2={{Clade
|1='''''Utahraptor'''''
|2=''[[Dromaeosaurus]]'' }} }}
|label2=[[Velociraptorinae]]
|2={{Clade
|1=''[[Adasaurus]]''
|2={{Clade
|label1=
|1={{Clade
|1=''[[Deinonychus]]''
|2=''[[Saurornitholestes]]'' }}
|label2=
|2={{Clade
|1=''[[Velociraptor]]''
|2={{Clade
|1=''[[Tsaagan]]''
|2=''[[Linheraptor]]''}}}}}}}}}}}}}}}}

==Paleobiology==
===Predatory behavior===
[[File:Utahraptor ostrommaysorum.JPG|thumb|Cast of the foot bones, [[Dinosaur Museum Aathal]]]]
Kirkland ''et al.'' noted that given the huge size of ''Utahraptor'', it was not as fast as ''[[Deinonychus]]'' and ''[[Velociraptor]];'' instead, it would have had a similar speed to the contemporary [[iguanodonts]], and was faster than [[sauropods]]. Additionally, the thickness of the [[tibia]] indicates that the animal possessed a significant leg force in order to kill prey. It was also suggested that lighter dromaeosaurids such as ''[[Velociraptor]]'' and ''[[Deinonychus]]'' relied on their hand claws to handle [[prey]] and retain balance while kicking it; in contrast to this, the heavily built ''Utahraptor'' may have been able to deliver kicks without the risk of losing balance, freeing the hands and using them to dispatch prey.<ref name="Kirkland93"/>

According to [[Gregory S. Paul]], ''Utahraptor'' was not particularly fast and would have been an [[ambush hunter]] that preyed on large dinosaurs such as the contemporary [[iguanodont]]s and [[therizinosaur]]s. Its robust build and large sickle claw indicate it was well suited to hunting such prey. Like other [[Dromaeosaurinae|dromaeosaurine]] dromaeosaurids, it may have also relied heavily on its jaws to dispatch prey—more so than other types of dromaeosaurids, such as [[Velociraptorinae|velociraptorines]].<ref name=Gregory2016>{{cite book|last=Paul|first=Gregory S.|author-link=Gregory S. Paul|title=The Princeton Field Guide to Dinosaurs|date=2016|publisher=Princeton University Press|location=Princeton, New Jersey|isbn=9780691167664|page=151|edition=2nd}}</ref>

===Social behavior===
In 2001, Kirkland ''et al.'' pursued a graduate student's discovery of a bone protruding from a 9-ton fossil block of [[sandstone]] in eastern Utah. It was determined to contain the bones of at least seven individuals, including an adult measuring about {{cvt|4.8|m}}, four juveniles, and a hatchling about {{cvt|1|m|ft}} long. Also fossilized with the ''Utahraptor'' pack are the remains of at least one possible [[iguanodont]]. Kirkland speculated that the ''Utahraptor'' pack attempted to scavenge carrion or attack helpless prey mired in quicksand, and were themselves mired in the attempt to feed on the herbivore. Similar sites such as the [[Cleveland-Lloyd Dinosaur Quarry|Cleveland-Lloyd Quarry]] and [[California]]'s [[La Brea Tar Pits]] house such predator traps. Examination of the fossils are ongoing after a decade of excavation, but if Kirkland is correct, it may be one of the best-preserved predator traps ever discovered. The fossils may further reveal aspects into the behavior of ''Utahraptor'', such as whether it might have hunted in groups like ''[[Deinonychus]]'' was believed to have done. Whether all the ''Utahraptor'' individuals were mired simultaneously or were drawn in, one-by-one is unclear.<ref name="KirklandTrap2016">{{cite journal |last1=Kirkland |first1=J.I. |author-link=James I. Kirkland |last2=Simpson |first2=E.L. |last3=DeBlieux |first3=D.D. |last4=Madsen |first4=S.K. |last5=Bogner |first5=E. |last6=Tibert |first6=N.E. |date=September 1, 2016 |title=Depositional constraints on the Lower Cretaceous stikes quarry dinosaur site: Upper yellow cat member, cedar mountain formation, Utah |url=https://www.researchgate.net/publication/308041652 |journal=PALAIOS |volume=31 |issue=9 |pages=421–439 |bibcode=2016Palai..31..421K |doi=10.2110/palo.2016.041 |s2cid=132388318}}</ref> Further examination of the block suggests that the number of ''Utahraptor'' remains may be double the amount previously assumed.<ref>{{Cite news|last=Williams|first=Carter|date=February 25, 2021|title=Several more Utahraptor fossils discovered from 136M-year-old block 1st found in Utah|work=KSL.com|publisher=[[Deseret Digital Media]]|url=https://www.ksl.com/article/50114561/several-more-utahraptor-fossils-discovered-from-136m-year-old-block-1st-found-in-utah|url-status=live|archive-url=https://web.archive.org/web/20210227110729/https://www.ksl.com/article/50114561/several-more-utahraptor-fossils-discovered-from-136m-year-old-block-1st-found-in-utah|archive-date=February 27, 2021}}</ref>

While dinosaur behavior can only be theorized, it was later discovered in 2020 that ''Deinonychus'' may not have practiced mammal-like pack hunting, based on differing dietary preferences in adults and juveniles. Despite this, the authors stated that gregariousness was still possible for ''Deinonychus'' and the discovery of ''Utahraptor'' in the mud-trap implies it exhibited a degree of post nestling care and gregariousness.<ref>{{cite journal |last1=Frederickson |first1=J. A. |last2=Engel |first2=M. H. |last3=Cifelli |first3=R. L. |title=Ontogenetic dietary shifts in Deinonychus antirrhopus (Theropoda; Dromaeosauridae): Insights into the ecology and social behavior of raptorial dinosaurs through stable isotope analysis |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |date=May 3, 2020 |volume=552 |pages=109780 |doi=10.1016/j.palaeo.2020.109780 |bibcode=2020PPP...55209780F |s2cid=219059665 }}</ref>

==Paleoenvironment==
''Utahraptor'' lived in the lower part of the [[Cedar Mountain Formation]], a bed known as the Yellow Cat Member. According to the authors of its description, ''Utahraptor'' had an important [[Biological interaction|ecological role]] as a major [[carnivore]] of the paleofauna of the present-day [[Arches National Park|Arches region]] during the [[Early Cretaceous]], and could probably attack prey larger than itself. Group hunting of individuals of at least {{cvt|3.5|m}} and {{cvt|70|kg}}, if proven, could have killed {{cvt|8|m}} prey of a weight of {{cvt|1|to|2|t|sigfig=2}}. Additionally, [[sauropods]] ranging around {{cvt|20|m}} may have been an important part of its diet.<ref name="Kirkland93"/> The [[paleontologist]] [[Thomas R. Holtz]] estimated that ''Utahraptor'' existed between 130 million and 125 million years ago.<ref name=Holtz2012>{{cite book|last1=Holtz|first1=T. R.|last2=Rey|first2=L. V.|title=Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages|date=2007|publisher=Random House}} [https://www.geol.umd.edu/~tholtz/dinoappendix/HoltzappendixWinter2011.pdf Supplementary Information 2012] [https://www.geol.umd.edu/~tholtz/dinoappendix/appendix.html Weight Information]</ref> In multiple occasions, the Yellow Cat Member has been dated to [[Barremian]]-[[Aptian]] ages. Sames and Schudack (2010) proposed a reassignment of the estimated age, compromising Berriasian to Valanginian stages; however, this interpretation was not followed by most authors.<ref>{{cite journal|last1=Sames|first1=B. C.|last2=Schudack|first2=M. E.|year=2010|title =The nonmarine Lower Cretaceous of the North American Western Interior foreland basin: new biostratigraphic results from ostracod correlations and early mammals, and their implications for paleontology and geology of the basin – an overview|journal=Earth-Science Reviews|volume=101|issue=3–4|pages=207–224|doi=10.1016/j.earscirev.2010.05.001|bibcode=2010ESRv..101..207S}}</ref> Using advanced methods of [[radiometric]] and [[palynological]] dating, Joeckel et al. (2019) concluded that the Yellow Cat Member is indeed older than previous estimations. The deposition occurred between 139 ± 1.3 million to 134.6 ± 1.7 million years ago, or, [[Berriasian]] to Late [[Valanginian]] stages. Based on the presence of new [[palynoflora]], Middle Berriasian–Early [[Hauterivian]] ages were provisionally assigned.<ref name=Joeckel2019>{{cite journal|last1=Joeckel|first1=R. M.|last2=Ludvigson|first2=G.|last3=Moeller|first3=A.|last4=Hotton|first4=C. L.|last5=Suarez|first5=M. B.|last6=Suarez|first6=C. A.|last7=Sames|first7=B.|last8=Kirkland|first8=J. I.|last9=Hendrix|first9=B.|title=Chronostratigraphy and Terrestrial Palaeoclimatology of Berriasian–Hauterivian Strata of the Cedar Mountain Formation, Utah, USA|doi=10.1144/SP498-2018-133|journal=Geological Society of London, Special Publications|year=2019|volume=498|pages=75–100|s2cid=210296827}}</ref> However, the Yellow Cat Member is divided into distinct "lower" and "upper" layers, and ''Utahraptor'' fossils are only currently known within the upper Yellow Cat Member.<ref name=Kirklandd2016>{{cite journal|first=J.I.|last=Kirkland|date=December 1, 2016|title=The Lower Cretaceous in East-Central Utah—The Cedar Mountain Formation and its Bounding Strata| journal=Geology of the Intermoutain West|volume=3|pages=1–130|url=https://www.researchgate.net/publication/312190529|url-access=<!--WP:URLACCESS-->}}</ref>

[[File:Cedar Mountain Formation Yellow Cat Fauna.png|upright=1.5|thumb|''Utahraptor'' (red, right) and other dinosaur fauna from the [[Cedar Mountain Formation]]]]
''Utahraptor'' was unearthed from the Yellow Cat Member, which during the [[Berriasian]] to Late [[Valanginian]] was a semiarid area with floodplain prairies, riverine forests, and open woodlands predominated by conifers ([[Pinophyta]]), ferns ([[Polypodiopsida]]), hornworts ([[Anthocerotophyta]]) and other [[vascular plant]]s.<ref name=Joeckel2019/> During the description of ''[[Mierasaurus]]'', it was interpreted that there was also a waterlogged bog-like environment.<ref name=Torres2017>{{cite journal |last1=Royo-Torres |first1=R. |last2=Upchurch |first2=P. |last3=Kirkland |first3=J.I. |last4=DeBlieux |first4=D.D. |last5=Foster |first5=J.R. |last6=Cobos |first6=A. |last7=Alcalá |first7=L. |year=2017 |title=Descendants of the Jurassic turiasaurs from Iberia found refuge in the Early Cretaceous of western USA |journal=Scientific Reports |volume=7 |issue=1 |pages=14311 |doi=10.1038/s41598-017-14677-2|pmid=29085006 |pmc=5662694 |bibcode=2017NatSR...714311R }}</ref> There is believed to have been a short wet season. This is supported by the presence of charred spores and other carbonized plant debris in the pollen maceral that indicate the occurrence of ancient wildfires ignited during periods of low precipitation.<ref name=Gregory2016/><ref name=Joeckel2019/>


[[Fauna|Paleofauna]] that were contemporaneous with the dromaeosaurid in the upper Yellow Cat Member included numerous dinosaurs, such as the medium-sized iguanodonts ''[[Hippodraco]]'' and ''[[Cedrorestes]]'', the smaller theropods ''[[Martharaptor]]'' and ''[[Nedcolbertia]]'', the [[nodosaurid]] ''[[Gastonia (dinosaur)|Gastonia]]'', and the [[sauropods]] ''[[Cedarosaurus]]'' and ''[[Moabosaurus]]''.<ref name=Torres2017/><ref name=Kirklandd2016/><ref name=":0">{{cite journal | last1 = Britt | first1 = B.B. | last2 = Scheetz | first2 = R.D. | last3 = Whiting | first3 = M.F. | last4 = Wilhite | first4 = D.R. | year = 2017 | title = Moabosaurus utahensis, n. gen., n. sp., A New Sauropod From The Early Cretaceous (Aptian) of North America | journal = Contributions from the Museum of Paleontology, University of Michigan | volume = 32 | issue = 11 | pages = 189–243 | s2cid = 50350241 | url = http://pdfs.semanticscholar.org/e691/f8450b199ed00df5f4667355238d5fb30ebd.pdf | archive-url = https://web.archive.org/web/20190305080534/http://pdfs.semanticscholar.org/e691/f8450b199ed00df5f4667355238d5fb30ebd.pdf | archive-date = 2019-03-05 }}</ref> The only known mammal from the Upper Yellow Cat Member is ''[[Cifelliodon]]''.<ref>{{cite journal |last1=Huttenlocker |first1=Adam K. |last2=Grossnickle |first2=David M. |last3=Kirkland |first3=James I. |author-link3=James I. Kirkland |last4=Schultz |first4=Julia A. |last5=Luo |first5=Zhe-Xi |date=May 23, 2018 |title=Late-surviving stem mammal links the lowermost Cretaceous of North America and Gondwana |journal=Nature |volume=558 |issue=7708 |pages=108–112 |bibcode=2018Natur.558..108H |doi=10.1038/s41586-018-0126-y |pmid=29795343 |s2cid=43921185}}</ref>
It is thought that ''Utahraptor'' may be closely related to the smaller ''[[Dromaeosaurus]]'' and the giant [[Mongolia]]n dromaeosaurid ''[[Achillobator]]''.<ref name="Kirkland93"/><ref name=turneretal2007a>{{cite journal |last=Turner |first=Alan H. |coauthors= Pol, D., Clarke, J.A., Erickson, G.M. and Norell, M. |year=2007 |title=A basal dromaeosaurid and size evolution preceding avian flight |url= |journal=Science |volume=317 |pages=1378–1381 |doi=10.1126/science.1144066 |pmid=17823350 |issue=5843 }}</ref>


Other non-dinosaur or [[Bird|avian]] taxa known from the Member include the [[fish]] ''[[Ceratodus (genus)|Ceratodus]]'' and ''[[Semionotus]]'', the [[turtles]] ''[[Glyptops]]'' and ''[[Trinitichelys]]'', [[Bird ichnology#Footprints|Aquatilavipes]] (fossilized bird tracks), the [[rhynchocephalian]] ''[[Toxolophosaurus]]'', and the indeterminate remains of [[hybodontid]] and [[polyacrodontid]] [[sharks]].<ref name=Kirklandd2016/>
Although feathers have never been found in association with ''Utahraptor'', there is strong phylogenetic evidence suggesting that all dromaeosaurids possessed them. This evidence comes from [[phylogenetic bracketing]], which allows paleontologists to infer traits that exist in a clade based on the existence of that trait in a more basal form. The genus ''[[Microraptor]]'' is one of the oldest known dromaeosaurids, and is phylogenetically more primitive than ''Utahraptor''.<ref>Xu, X., Zhou, Z., Wang, X., Kuang, X., Zhang, F. and Du, X. (2003). "Four-winged dinosaurs from China." Nature, 421(6921): 335-340, 23 Jan 2003. http://www.nature.com/nature/journal/v421/n6921/full/nature01342.html</ref> Since ''Microraptor'' possessed feathers, it is reasonable to assume that this trait was present in all of Dromaeosauridae. Feathers were very unlikely to have evolved more than once in dromaeosaurs, so assuming that ''Utahraptor'' lacked feathers would require positive evidence that it did not have them.<ref>Prum, R. & Brush A.H. (2002). "The evolutionary origin and diversification of feathers". The Quarterly Review of Biology 77: 261–295. doi:10.1086/341993.</ref> So far, there is nothing to suggest that feathers were lost in larger, more derived species of dromaeosaurs.<ref>Turner, A.H.; Makovicky, P.J.; Norell, M.A. (2007). "Feather quill knobs in the dinosaur Velociraptor". Science 317 (5845): 1721. doi:10.1126/science.1145076. PMID 17885130.</ref>


Additional [[Fauna|paleofauna]] was recovered, most of it being unnamed and/or indeterminate, including an isolated [[mesoeucrocodylia]]n skull that measures {{cvt|20|cm}} in length.<ref name=Kirklandd2016/> A [[neochoristodere]] unearthed from the Upper Yellow Cat Member, represented by a partial left femur,<ref>{{cite journal |last1=Britt |first1=Brooks B. |last2=Scheetz |first2=Rodney D. |last3=Brinkman |first3=Donald B. |last4=Eberth |first4=David A. |title=A Barremian neochoristodere from the Cedar Mountain Formation, Utah, U.S.A. |journal=Journal of Vertebrate Paleontology |date=December 11, 2006 |volume=26 |issue=4 |pages=1005–1008 |doi=10.1671/0272-4634(2006)26[1005:ABNFTC]2.0.CO;2 |s2cid=86258448 }}</ref> shows that aquatic paleofauna was present and diverse during the Early Cretaceous of the Cedar Mountain Formation.<ref name=Kirklandd2016/> A large sail-backed iguanodont represented by large vertebrae and fragmentary remains,<ref>{{cite journal|first1=R. A.|last1=Scheetz|first2=B. B.|last2=Britt|first3=J.|last3=Higgerson|year=2010|title=A large, tall-spined iguanodontid dinosaur from the Early Cretaceous (Early Albian) basal Cedar Mountain Formation of Utah|journal=Journal of Vertebrate Paleontology|volume=30|issue=Supplement 2|pages=158A|doi=10.1080/02724634.2010.10411819|s2cid=220429286}}</ref> and an indeterminate [[eudromaeosaur]] known from a [[caudal vertebra]] and fragmented tail (UMNH VP 20209) were also present.<ref>{{cite journal |last1=Senter |first1=P. |last2=Kirkland |first2=J. I. |author-link2=James I. Kirkland |last3=Deblieux |first3=D. D. |last4=Madsen |first4=S. |last5=Toth |first5=N. |year=2012 |editor1-last=Dodson |editor1-first=Peter |editor-link=Peter Dodson |title=New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the Evolution of the Dromaeosaurid Tail |journal=PLOS ONE |volume=7 |issue=5 |pages=e36790 |bibcode=2012PLoSO...736790S |doi=10.1371/journal.pone.0036790 |pmc=3352940 |pmid=22615813 |doi-access=free}}</ref>
==Discovery==
[[James Kirkland (paleontologist)|James Kirkland]], Robert Gaston, and Donald Burge discovered ''Utahraptor'' in 1991 in [[Grand County, Utah|Grand County]], [[Utah]], within the Yellow Cat and Poison Strip members of the [[Cedar Mountain Formation]].<ref name="Kirkland93">{{Cite journal | last1 = Kirkland | first1 = J.I. | last2 = Burge | first2 = D. | last3 = Gaston | first3 = R. | year = 1993 | title = A large dromaeosaur [Theropoda] from the Lower Cretaceous of Utah | url = | journal = Hunteria | volume = 2 | issue = 10| pages = 1–16 }}</ref> Radiometric dating has shown that these parts of the Cedar Mountain Formation were deposited about 126 million years ago.<ref name="kirklandmadsen2007">Kirkland, J.I. and Madsen, S.K. 2007. The Lower Cretaceous Cedar Mountain Formation, eastern Utah: the view up an always interesting learning curve. Fieldtrip Guidebook, Geological Society of America, Rocky Mountain Section. 1-108 p.</ref> The [[type specimen]] is currently housed at the [[College of Eastern Utah Prehistoric Museum]], although [[Brigham Young University]] currently houses the largest collection of ''Utahraptor'' fossils.


==Cultural significance==
The [[Type (biology)|type species]] (and only known species of ''Utahraptor''), ''Utahraptor ostrommaysorum'', was named for the [[United States|American]] [[paleontologist]] [[John Ostrom]], from Yale University's [[Peabody Museum of Natural History]], and Chris Mays, of [[Dinamation]] International. Sculptor [[Raymond Persinger]] was included in James Kirkland's original abstract referencing Mr. Persinger's concepts regarding the claw structure.
''[[Raptor Red]]'' was published in 1995, and features the fictionalized story of a female ''Utahraptor''. Written by paleontologist [[Robert T. Bakker]], it was positively regarded by mainstream reviewers, though updates to the science have rendered some of the story line facts presented untrue and the paleontology community was critical of fossil record inaccuracies.<ref>{{cite web | title = ''Raptor Red'': a review (long) | author = Holtz, Thomas R. | date = September 12, 1995 | website = Archives of the DINOSAUR Mailing List | url = http://dml.cmnh.org/1995Sep/msg00258.html | access-date = December 5, 2014 | archive-date = March 3, 2021 | archive-url = https://web.archive.org/web/20210303143128/http://dml.cmnh.org/1995Sep/msg00258.html | url-status = dead }}</ref><ref name="earth-kanipe">{{cite journal|author=Kanipe, Jeff|date=February 1996|title=Dino Redux|journal=Earth|volume=5|issue=1|pages=66–68}}</ref> Bakker's anthropomorphosis of the titular Red was particularly praised.<ref name="thetimes-monster">{{cite news|last=Naughton|first=John|date=September 5, 1995|title=At home with a Jurassic monster|work = [[The Times]]}}</ref><ref name="globe-alone">{{cite news |last=Chander |first=David |date=November 13, 1995 |title=In his field, Robert Bakker walks alone |work=Boston Globe |page=29}}</ref><ref>{{cite journal|author=Johnson, Eric|date=September 1995|title=Book Reviews: Fiction|journal=[[Library Journal]]|volume=120|issue=14|page=205}}</ref>


In 2018, it was proposed by a 10-year-old elementary school student, Kenyon Roberts, that ''Utahraptor'' be the Utah [[List of U.S. state dinosaurs|state dinosaur]], an act that was approved by the [[Utah State Senate|Senate]].<ref>{{cite web |last=Nixon |first=Nicole |date=February 12, 2018 |title=Senate Gives ''Utahraptor'' A Roar Of Approval |url=http://kuer.org/post/senate-gives-utahraptor-roar-approval#stream/0 |access-date=February 13, 2018 |website=kuer.org}}</ref> Initially ''Utahraptor'' would have replaced another dinosaur, ''[[Allosaurus]]'', as the [[List of U.S. state fossils|state's official fossil]], but it was decided that ''Utahraptor'' would be another symbol of the state.<ref>{{cite web |last=Roche |first=Lisa Riley |date=February 12, 2018 |title=Senate approves bill making ''Utahraptor'' state dinosaur |url=https://www.deseretnews.com/article/900010113/senate-approves-bill-making-utahraptor-state-dinosaur.html |archive-url=https://web.archive.org/web/20180215040843/https://www.deseretnews.com/article/900010113/senate-approves-bill-making-utahraptor-state-dinosaur.html |url-status=dead |archive-date=February 15, 2018 |access-date=February 18, 2018 |website=[[Deseret News]]}}</ref> In 2021, [[Steve Eliason]]<ref>{{Cite web |last1=Eliason |first1=Steve |author-link=Steve Eliason |last2=Iwamoto |first2=Jani |author-link2=Jani Iwamoto |date=2020 |title=H.B. 322 - Utahraptor State Park |url=https://le.utah.gov/~2020/bills/enwiki/static/HB0322.html |website=Utah State Legislature}}</ref><ref>{{Cite news |last=McKellar |first=Katie |date=February 18, 2020 |title=Utahraptor State Park would protect discovery site of Utah's namesake dinosaur |url=https://www.deseret.com/utah/2020/2/18/21138197/utahraptor-state-park-would-protect-discovery-site-of-utahs-namesake-dinosaur |access-date=January 17, 2024 |work=Deseret News}}</ref> successfully created a proposal for [[Utahraptor State Park]] where the block was discovered, proposed by the same Utah student, Kenyon Roberts. It was approved by the state House.<ref>{{Cite web |last=Johnson |first=Jan |date=March 2, 2021 |title=Utah Considers State Park Named For Utahraptor Dinosaur |url=https://www.npr.org/2021/03/02/972905995/utah-considers-state-park-named-for-utahraptor-dinosaur |access-date=2021-03-04 |website=NPR.org |language=en}}</ref>
==In popular culture==
[[File:Utahraptor foot.JPG|thumb|left|150px|Model of the foot, showing specialized claw]]
A speculative reconstruction of ''Utahraptor'' lifestyles and behavior was presented in the 1999 [[BBC]] television series ''[[Walking with Dinosaurs]]''.<ref name=WWDmedia>"Unnatural history? Deconstructing the ''Walking with
Dinosaurs'' phenomenon." ''Media Culture & Society'', '''25'''(3): 315-332. {{doi|10.1177/0163443703025003002}}</ref> The program portrayed ''Utahraptor'' with several anatomical inaccuracies including [[Pronation|pronated]] hands, and depicted it living in Europe when the only fossils of ''Utahraptor'' have been found in western North America.<ref name=WWDnathist>Haines, T. (2000). ''Walking with Dinosaurs: A Natural History''. London: BBC Publishing.</ref>


==See also==
Ryan North's award-winning "[[Dinosaur Comics]]" online comic strip prominently features a ''Utahraptor''. The ''Utahraptor'' character is meant to serve as a "questioning and interrogative" interlocutor in the comic's sometimes bizarre discussions of life and philosophy.<ref name="Ryan North Interview">Whaley, K. (2006). "[http://torontoist.com/2006/05/tall_poppy_inte_31.php Tall Poppy Interview: Ryan North of Dinosaur Comics]." ''The Torontoist'', 17 May 2006. accessed online 16 Sep 2010, http://torontoist.com/2006/05/tall_poppy_inte_31.php.</ref>
* [[Timeline of dromaeosaurid research]]


==References==
==References==
{{Reflist}}
{{Reflist}}


==External links==
{{Commons category|Utahraptor}}
* {{Commons category-inline|Utahraptor|''Utahraptor''}}
{{Portal|Dinosaurs}}
* {{Wikispecies-inline|Utahraptor|''Utahraptor''}}
* [https://www.facebook.com/The-Utahraptor-Project-1740182959575280/ ''Utahraptor'' Project page] at [[Facebook]]
* [https://www.skeletaldrawing.com/theropods/utahraptor ''Utahraptor'' skeletal reconstruction] by [[Scott Hartman]]
* [https://sketchfab.com/3d-models/utahraptor-skeleton-3d82f62a6e924ee5bb25fd8f368d02bc 3D ''Utahraptor'' skeletal reconstruction] at [[Sketchfab]]


{{Dromaeosauridae}}
[[Category:Cretaceous dinosaurs]]
[[Category:Dinosaurs of North America]]
{{Portal bar|Dinosaurs|United States}}
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[[Category:Dromaeosaurs]]
[[Category:Natural history of Utah]]


[[Category:Early Cretaceous dinosaurs of North America]]
[[ca:Utahraptor]]
[[Category:Eudromaeosaurs]]
[[cs:Utahraptor]]
[[Category:Extinct animals of Utah]]
[[da:Utahraptor]]
[[Category:Fossil taxa described in 1993]]
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[[Category:Taxa named by James I. Kirkland]]
[[es:Utahraptor]]
[[Category:Paleontology in Utah]]
[[fr:Utahraptor]]
[[Category:Valanginian life]]
[[ko:유타랍토르]]
[[Category:Apex predators]]
[[it:Utahraptor ostrommaysorum]]
[[Category:Symbols of Utah]]
[[he:יוטרפטור]]
[[Category:Feathered dinosaurs]]
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[[Category:Valanginian genus extinctions]]
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Latest revision as of 11:39, 25 December 2024

Utahraptor
Temporal range: Early Cretaceous (BerriasianValanginian), 139–134.6 Ma
Reconstructed skeleton in BYU Museum of Paleontology
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: Dromaeosauridae
Clade: Eudromaeosauria
Subfamily: Dromaeosaurinae
Genus: Utahraptor
Kirkland, Gaston & Burge, 1993
Type species
Utahraptor ostrommaysi
Kirkland et al., 1993

Utahraptor (meaning "Utah's predator") is a genus of large dromaeosaurid (a group of feathered carnivorous theropods) dinosaur that lived during the Early Cretaceous period from around 135 to 130 million years ago in what is now the United States. The genus was described in 1993 by American paleontologist James Kirkland and colleagues with the type species Utahraptor ostrommaysi, based on fossils that had been unearthed earlier from the Cedar Mountain Formation of Utah. Later, many additional specimens were described including those from the skull and postcranium in addition to those of younger individuals.

The genus contains a single species, Utahraptor ostrommaysi. It is the largest-known member of the family Dromaeosauridae, measuring about 6–7 metres (20–23 ft) long and typically weighing less than 500 kilograms (1,100 lb). As a heavily built, ground-dwelling, bipedal carnivore, its large size and variety of unique features have earned it attention in both pop culture and the scientific community. The jaws of Utahraptor were lined with small, serrated teeth that were used in conjunction with a large "killing claw" on its second toe to dispatch its prey. Its skull was boxy and elongated, akin to other dromaeosaurids like Dromaeosaurus and Velociraptor.

Being a carnivore, Utahraptor was adapted to hunt the other animals of the Cedar Mountain Formation ecosystem such as ankylosaurs and iguanodonts. Evidence from the leg physiology supports the idea of Utahraptor being an ambush predator, in contrast to other dromaeosaurs that were pursuit predators.

Discovery and naming

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Premaxilla of BYU 7510 14585

The first specimens of Utahraptor were found in 1975 by Jim Jensen in the Dalton Wells Quarry of Utah, near the town of Moab, but did not receive much attention. After a find of a large claw by Carl Limone in October 1991, James Kirkland, Robert Gaston and Donald Burge uncovered further remains of Utahraptor in 1991 in the Gaston Quarry in Grand County, Utah, within the Yellow Cat and Poison Strip members of the Cedar Mountain Formation. The holotype of Utahraptor, CEUM 184v.86, consists of a second pedal ungual, with potentially assigned elements from other specimens: pedal ungual CEUM 184v.294, tibia CEUM 184v.260 and premaxilla CEUM 184v.400.[1] The holotype is housed in the paleontology collections of the Prehistoric Museum at Utah State University Eastern. Brigham Young University, the depository of Jensen's finds, currently houses the largest collection of Utahraptor fossils. [1]

The type species, Utahraptor ostrommaysi, was named by Kirkland, Gaston and Burge in June 1993. The genus name Utahraptor is in reference to Utah, where the remains were found. The specific name, ostrommaysi, is in honor to John Ostrom for his investigations on Deinonychus and its relationships to birds, as well as Chris Mays, who helped in the research of Utahraptor by founding Dinamation.[1] From his description, Kirkland stated the meaning of genus name to be "Utah's predator,"[1] but the Latin word raptor translates to 'robber' or 'plunderer', not 'predator'.[2] Earlier, it had been intended to name the species "U. spielbergi" after film director Steven Spielberg, in exchange for him funding paleontological research, but no agreement could be reached on the amount of financial assistance.[3]

Pedal ungual II of CEUM 184v.294, housed at the Prehistoric Museum, USU Eastern.

In 2000, the specific name was emended by George Olshevsky to the plural genitive ostrommaysorum.[4] However, Thiago Vernaschi V. Costa and Normand David in 2019 criticized the use of the species name U. ostrommaysorum, since it has no clear justification or explanation. Although this spelling has been largely used by other authors, the genus Utahraptor was originally coined with the type species U. ostrommaysi and, given that the International Code of Zoological Nomenclature offers no provision for forming a genitive form from two persons with different names, Costa and David conclude that the original spelling ostrommaysi has to be regarded as an arbitrary combination of letters and not a correctly formed genitive form. Under this reasoning, ostrommaysorum has no valid use and the original spelling ostrommaysi does not need to be emended. Other alternative and also invalid spellings were used in scientific literature, such as ostromaysi, ostromaysorum, ostromayssorum, ostromayorum and ostrommaysori.[5]

Some elements were wrongly referred to the genus. The lacrimal bone of the specimen CEUM 184v.83 turned out to be a postorbital from the ankylosaur Gastonia. Britt et al. also suggested that the previously identified manual unguals of the specimens M184v.294, BYU 9438 and BYU 13068 are indeed pedal unguals.[6] This suggestion was confirmed by Senter in 2007.[7]

Description

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Restoration
Utahraptor specimens compared in size to a 1.8-metre-tall (5.9 ft) human

Utahraptor was one of, if not the largest and heaviest of all dromaeosaurids, with the largest assigned specimen BYUVP 15465 having a femoral length of 56.5–60 cm (22.2–23.6 in).[8][9]

Utahraptor is estimated to have reached 6–7 metres (20–23 ft) in length and somewhat less than 500 kg (1,100 lb), comparable in weight to a polar bear.[1][10][11] Some authors estimated that it weighed up to 250–350 kg (550–770 lb).[12][13][14] In 2024, the body mass of BYUVP 2536 and BYUVP 1833 were estimated around 391 and 481 kilograms (862 and 1,060 lb) respectively, though BYUVP 7510-18078 was estimated to have weighed 777 kilograms (1,713 lb).[15]

Although feathers have never been found in association with Utahraptor specimens, there is strong phylogenetic evidence suggesting that all dromaeosaurids had them. The feathered genus Microraptor is one of the oldest-known dromaeosaurids and is phylo­genetically more primitive than Utahraptor.[16] Since Microraptor and other dromaeosaurids possessed feathers, it is reasonable to assume that this trait was present in all of Dromaeosauridae. Feathers were very unlikely to have evolved more than once, so assuming that any given dromaeosaurid, such as Utahraptor, lacked feathers would require positive evidence that they did not have them.[17] So far, there is nothing to suggest that feathers were lost in larger, more derived species of dromaeosaurs.[18] The presence of quill knobs in Dakotaraptor evidenced that even larger dromaeosaurids had feathers.[19]

Reconstructed skull, BYU

According to Kirkland et al. in 1993, Utahraptor can be recognized by a few special autapomorphies. The claws on its hand are more specialized as cutting blades than in other dromaeosaurids. It has a lacrimal bone with distinctly parallel mesial and outer sides that gives it an elongate subrectangular appearance in top view and it has a base of the nasal opening on the premaxilla parallel to the premaxillary tooth row.[1] In the revised diagnosis conducted by Turner et al. in 2012, Utahraptor differs from other dromaeosaurids in having an elongate nasal process of the premaxilla, a distal end of metatarsal III that is smooth, not ginglymoid, an L-shaped quadratojugal without a posterior process, the presence of a well-developed notch between the lesser trochanter and greater trochanter, and dorsal vertebrae that lack pleurocoels.[20] Like other dromaeosaurids, Utahraptor had a large curved claw on the second toe of each foot. The second pedal ungual is preserved with a 22 cm (8.7 in) outside curve length and is estimated to reach 24 cm (9.4 in) in restoration.[1]

Classification

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Utahraptor is a member of the family Dromaeosauridae, a clade of theropod dinosaurs commonly known as "raptors". Utahraptor is the largest known genus in the family and belongs to the same clade of other notable dinosaurs such as Velociraptor, Deinonychus, or Dromaeosaurus. It is classified in the subfamily Dromaeosaurinae, which is found in the clade Eudromaeosauria.[1]

In 2015, Utahraptor was found to be closely related to the smaller Dromaeosaurus and the giant Mongolian and North American dromaeosaurid genera Achillobator and Dakotaraptor:[19]

Size of Utahraptor (5) compared with other dromaeosaurs
Eudromaeosauria

The cladogram below is the result of a cladistic analysis conducted by Cau et al. in 2017.[21]

Paleobiology

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Predatory behavior

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Cast of the foot bones, Dinosaur Museum Aathal

Kirkland et al. noted that given the huge size of Utahraptor, it was not as fast as Deinonychus and Velociraptor; instead, it would have had a similar speed to the contemporary iguanodonts, and was faster than sauropods. Additionally, the thickness of the tibia indicates that the animal possessed a significant leg force in order to kill prey. It was also suggested that lighter dromaeosaurids such as Velociraptor and Deinonychus relied on their hand claws to handle prey and retain balance while kicking it; in contrast to this, the heavily built Utahraptor may have been able to deliver kicks without the risk of losing balance, freeing the hands and using them to dispatch prey.[1]

According to Gregory S. Paul, Utahraptor was not particularly fast and would have been an ambush hunter that preyed on large dinosaurs such as the contemporary iguanodonts and therizinosaurs. Its robust build and large sickle claw indicate it was well suited to hunting such prey. Like other dromaeosaurine dromaeosaurids, it may have also relied heavily on its jaws to dispatch prey—more so than other types of dromaeosaurids, such as velociraptorines.[22]

Social behavior

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In 2001, Kirkland et al. pursued a graduate student's discovery of a bone protruding from a 9-ton fossil block of sandstone in eastern Utah. It was determined to contain the bones of at least seven individuals, including an adult measuring about 4.8 m (16 ft), four juveniles, and a hatchling about 1 m (3.3 ft) long. Also fossilized with the Utahraptor pack are the remains of at least one possible iguanodont. Kirkland speculated that the Utahraptor pack attempted to scavenge carrion or attack helpless prey mired in quicksand, and were themselves mired in the attempt to feed on the herbivore. Similar sites such as the Cleveland-Lloyd Quarry and California's La Brea Tar Pits house such predator traps. Examination of the fossils are ongoing after a decade of excavation, but if Kirkland is correct, it may be one of the best-preserved predator traps ever discovered. The fossils may further reveal aspects into the behavior of Utahraptor, such as whether it might have hunted in groups like Deinonychus was believed to have done. Whether all the Utahraptor individuals were mired simultaneously or were drawn in, one-by-one is unclear.[23] Further examination of the block suggests that the number of Utahraptor remains may be double the amount previously assumed.[24]

While dinosaur behavior can only be theorized, it was later discovered in 2020 that Deinonychus may not have practiced mammal-like pack hunting, based on differing dietary preferences in adults and juveniles. Despite this, the authors stated that gregariousness was still possible for Deinonychus and the discovery of Utahraptor in the mud-trap implies it exhibited a degree of post nestling care and gregariousness.[25]

Paleoenvironment

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Utahraptor lived in the lower part of the Cedar Mountain Formation, a bed known as the Yellow Cat Member. According to the authors of its description, Utahraptor had an important ecological role as a major carnivore of the paleofauna of the present-day Arches region during the Early Cretaceous, and could probably attack prey larger than itself. Group hunting of individuals of at least 3.5 m (11 ft) and 70 kg (150 lb), if proven, could have killed 8 m (26 ft) prey of a weight of 1 to 2 t (0.98 to 2.0 long tons; 1.1 to 2.2 short tons). Additionally, sauropods ranging around 20 m (66 ft) may have been an important part of its diet.[1] The paleontologist Thomas R. Holtz estimated that Utahraptor existed between 130 million and 125 million years ago.[26] In multiple occasions, the Yellow Cat Member has been dated to Barremian-Aptian ages. Sames and Schudack (2010) proposed a reassignment of the estimated age, compromising Berriasian to Valanginian stages; however, this interpretation was not followed by most authors.[27] Using advanced methods of radiometric and palynological dating, Joeckel et al. (2019) concluded that the Yellow Cat Member is indeed older than previous estimations. The deposition occurred between 139 ± 1.3 million to 134.6 ± 1.7 million years ago, or, Berriasian to Late Valanginian stages. Based on the presence of new palynoflora, Middle Berriasian–Early Hauterivian ages were provisionally assigned.[28] However, the Yellow Cat Member is divided into distinct "lower" and "upper" layers, and Utahraptor fossils are only currently known within the upper Yellow Cat Member.[29]

Utahraptor (red, right) and other dinosaur fauna from the Cedar Mountain Formation

Utahraptor was unearthed from the Yellow Cat Member, which during the Berriasian to Late Valanginian was a semiarid area with floodplain prairies, riverine forests, and open woodlands predominated by conifers (Pinophyta), ferns (Polypodiopsida), hornworts (Anthocerotophyta) and other vascular plants.[28] During the description of Mierasaurus, it was interpreted that there was also a waterlogged bog-like environment.[30] There is believed to have been a short wet season. This is supported by the presence of charred spores and other carbonized plant debris in the pollen maceral that indicate the occurrence of ancient wildfires ignited during periods of low precipitation.[22][28]

Paleofauna that were contemporaneous with the dromaeosaurid in the upper Yellow Cat Member included numerous dinosaurs, such as the medium-sized iguanodonts Hippodraco and Cedrorestes, the smaller theropods Martharaptor and Nedcolbertia, the nodosaurid Gastonia, and the sauropods Cedarosaurus and Moabosaurus.[30][29][31] The only known mammal from the Upper Yellow Cat Member is Cifelliodon.[32]

Other non-dinosaur or avian taxa known from the Member include the fish Ceratodus and Semionotus, the turtles Glyptops and Trinitichelys, Aquatilavipes (fossilized bird tracks), the rhynchocephalian Toxolophosaurus, and the indeterminate remains of hybodontid and polyacrodontid sharks.[29]

Additional paleofauna was recovered, most of it being unnamed and/or indeterminate, including an isolated mesoeucrocodylian skull that measures 20 cm (7.9 in) in length.[29] A neochoristodere unearthed from the Upper Yellow Cat Member, represented by a partial left femur,[33] shows that aquatic paleofauna was present and diverse during the Early Cretaceous of the Cedar Mountain Formation.[29] A large sail-backed iguanodont represented by large vertebrae and fragmentary remains,[34] and an indeterminate eudromaeosaur known from a caudal vertebra and fragmented tail (UMNH VP 20209) were also present.[35]

Cultural significance

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Raptor Red was published in 1995, and features the fictionalized story of a female Utahraptor. Written by paleontologist Robert T. Bakker, it was positively regarded by mainstream reviewers, though updates to the science have rendered some of the story line facts presented untrue and the paleontology community was critical of fossil record inaccuracies.[36][37] Bakker's anthropomorphosis of the titular Red was particularly praised.[38][39][40]

In 2018, it was proposed by a 10-year-old elementary school student, Kenyon Roberts, that Utahraptor be the Utah state dinosaur, an act that was approved by the Senate.[41] Initially Utahraptor would have replaced another dinosaur, Allosaurus, as the state's official fossil, but it was decided that Utahraptor would be another symbol of the state.[42] In 2021, Steve Eliason[43][44] successfully created a proposal for Utahraptor State Park where the block was discovered, proposed by the same Utah student, Kenyon Roberts. It was approved by the state House.[45]

See also

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References

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  2. ^ "raptŏr - ONLINE LATIN DICTIONARY". Online Latin Dictionary.
  3. ^ Adams, Brooke (June 15, 1993). "Director Loses Utahraptor Name Game". Deseret News. Archived from the original on October 23, 2016.
  4. ^ Olshevsky, G., 2000, An annotated checklist of dinosaur species by continent. Mesozoic Meanderings 3: 1-157
  5. ^ Costa, T. V. V.; David, N. (2019). "Commentaries on different uses of the specific epithet of the large dromaeosaurid Utahraptor Kirkland et al., 1993 (Dinosauria, Theropoda)". The Bulletin of Zoological Nomenclature. 76 (1): 90−96. doi:10.21805/bzn.v76.a028. S2CID 166691677.
  6. ^ Britt, B. B.; Chure, D. J.; Stadtman, K. L.; Madsen, J. H.; Scheetz, R. D.; Burge, D. L. (2001). "New osteological data and the affinities of Utahraptor from the Cedar Mountain Fm. (Early Cretaceous) of Utah". Journal of Vertebrate Paleontology. 21 (3): 36A.
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  9. ^ Sues, Hans-Dieter; Averianov, Alexander; Britt, Brooks B. (December 22, 2022). "A giant dromaeosaurid theropod from the Upper Cretaceous (Turonian) Bissekty Formation of Uzbekistan and the status of Ulughbegsaurus uzbekistanensis". Geological Magazine. 160 (2): 355–360. doi:10.1017/S0016756822000954. ISSN 0016-7568.
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  21. ^ Cau, Andrea; Beyrand, Vincent; Voeten, Dennis F. A. E.; Fernandez, Vincent; Tafforeau, Paul; Stein, Koen; Barsbold, Rinchen; Tsogtbaatar, Khishigjav; Currie, Philip J.; Godefroit, Pascal (December 6, 2017). "Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs". Nature. 552 (7685): 395–399. Bibcode:2017Natur.552..395C. doi:10.1038/nature24679. PMID 29211712. S2CID 4471941.
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  24. ^ Williams, Carter (February 25, 2021). "Several more Utahraptor fossils discovered from 136M-year-old block 1st found in Utah". KSL.com. Deseret Digital Media. Archived from the original on February 27, 2021.
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  41. ^ Nixon, Nicole (February 12, 2018). "Senate Gives Utahraptor A Roar Of Approval". kuer.org. Retrieved February 13, 2018.
  42. ^ Roche, Lisa Riley (February 12, 2018). "Senate approves bill making Utahraptor state dinosaur". Deseret News. Archived from the original on February 15, 2018. Retrieved February 18, 2018.
  43. ^ Eliason, Steve; Iwamoto, Jani (2020). "H.B. 322 - Utahraptor State Park". Utah State Legislature.
  44. ^ McKellar, Katie (February 18, 2020). "Utahraptor State Park would protect discovery site of Utah's namesake dinosaur". Deseret News. Retrieved January 17, 2024.
  45. ^ Johnson, Jan (March 2, 2021). "Utah Considers State Park Named For Utahraptor Dinosaur". NPR.org. Retrieved March 4, 2021.
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