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{{Automatic taxobox
{{Automatic taxobox
| name = Sauropodomorphs
| name = Sauropodomorphs
| fossil_range = {{fossil range|233.23|66|ref=<ref name=langer18>{{cite journal|last1=Langer|first1=M.C.|last2=Ramezani|first2=J.|last3=Da Rosa|first3=Á.A.S.|year=2018|title=U-Pb age constraints on dinosaur rise from south Brazil|journal=Gondwana Research|volume=X|issue=18|pages=133–140|doi=10.1016/j.gr.2018.01.005|bibcode=2018GondR..57..133L}}</ref>}}
| fossil_range = {{fossil range|233.23|66}}
| image = Sauropodomorpha.jpg
| image = Sauropodomorpha Infobox Panoply.png
| image_caption = Six sauropodomorphs (top left to bottom right): ''[[Plateosaurus]]'', ''[[Brontosaurus]]'', ''[[Massospondylus]]'', ''[[Eoraptor]]'', ''[[Thecodontosaurus]]'', ''[[Cetiosaurus]]''
| image_alt =
| image_upright = 1.3
| image_caption = Montage of nine different representatives of sauropodomorph dinosaurs. Clockwise from upper left: ''[[Eoraptor lunensis]]'', ''[[Plateosaurus engelhardti]]'', ''[[Brontosaurus excelsus]]'', ''[[Europasaurus holgeri]]'', ''[[Mamenchisaurus hochuanensis]]'', ''[[Nigersaurus taqueti]]'', ''[[Argentinosaurus huinculensis]]'', ''[[Diplodocus carnegii]]'', ''[[Brachiosaurus altithorax]]''.
| taxon = Sauropodomorpha
| taxon = Sauropodomorpha
| authority = [[Friedrich von Huene|Huene]], 1932
| authority = [[Friedrich von Huene|Huene]], 1932
| subdivision_ranks = Subgroups
| subdivision_ranks = Subgroups
| subdivision = * {{extinct}}''[[Buriolestes]]''
| subdivision =
* {{extinct}}''[[Buriolestes]]''
* {{extinct}}''[[Eoraptor]]''
* {{extinct}}''[[Eoraptor]]''
* {{extinct}}''[[Mbiresaurus]]''
* {{extinct}}''[[Mbiresaurus]]''
* {{extinct}}[[Saturnaliidae]]
* {{extinct}}'''[[Saturnaliidae]]'''
* {{extinct}}[[Guaibasauridae]]
* {{extinct}}'''[[Guaibasauridae]]'''
* {{extinct}}'''Bagualosauria''' <small>Langer ''et al.'', 2019</small>
* {{extinct}}'''Bagualosauria''' <small>Langer ''et al.'', 2019</small>
** {{extinct}}''[[Arcusaurus]]''
** {{extinct}}''[[Arcusaurus]]''
** {{extinct}}''[[Asylosaurus]]''
** {{extinct}}''[[Asylosaurus]]''
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** {{extinct}}''[[Nambalia]]''
** {{extinct}}''[[Nambalia]]''
** {{extinct}}''[[Pantydraco]]''
** {{extinct}}''[[Pantydraco]]''
** {{extinct}}[[Thecodontosauridae]]
** {{extinct}}'''[[Thecodontosauridae]]'''
** {{extinct}}[[Unaysauridae]]
** {{extinct}}'''[[Unaysauridae]]'''
** {{extinct}}[[Plateosauria]]
** {{extinct}}'''Plateosauria''' <small>[[Gustav Tornier|Tornier]], 1913</small>
*** {{extinct}}''[[Plateosauravus]]''
*** {{extinct}}''[[Ruehleia]]''
*** {{extinct}}''[[Xixiposaurus]]''
*** {{extinct}}'''[[Plateosauridae]]'''
*** {{extinct}}'''[[Massopoda]]'''
}}
}}


'''Sauropodomorpha''' ({{IPAc-en|ˌ|s|ɔːr|ə|ˌ|p|ɒ|d|ə|ˈ|m|ɔːr|f|ə}}{{refn|Cf. {{cite web |url=https://www.oxforddictionaries.com/definition/english/sauropodomorph |archive-url=https://web.archive.org/web/20151101224803/http://www.oxforddictionaries.com/definition/english/sauropodomorph |url-status=dead |archive-date=November 1, 2015 |title=sauropodomorph - definition of sauropodomorph in English from the Oxford dictionary |publisher=[[OxfordDictionaries.com]] |access-date=2016-01-20 }}}} {{respell|SOR|ə|POD|ə|MOR|fə}}; from Greek, meaning "lizard-footed forms") is an extinct [[clade]] of long-necked, [[herbivorous]], [[saurischian]] [[dinosaur]]s that includes the [[Sauropoda|sauropod]]s and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were [[quadruped]]al, and became the largest animals to ever walk the Earth. The ''[[prosauropods]],'' which preceded the sauropods, were smaller and were often able to walk on [[bipedal|two legs]]. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the [[Mesozoic Era]], from their origins in the [[Late Triassic]] (approximately 230 [[Myr|Ma]]) until their decline and [[Cretaceous-Paleogene extinction event|extinction]] at the end of the [[Cretaceous]].
'''Sauropodomorpha''' ({{IPAc-en|ˌ|s|ɔːr|ə|ˌ|p|ɒ|d|ə|ˈ|m|ɔːr|f|ə}}{{refn|Cf. {{cite web |url=https://www.oxforddictionaries.com/definition/english/sauropodomorph |archive-url=https://web.archive.org/web/20151101224803/http://www.oxforddictionaries.com/definition/english/sauropodomorph |url-status=dead |archive-date=November 1, 2015 |title=sauropodomorph - definition of sauropodomorph in English from the Oxford dictionary |publisher=[[OxfordDictionaries.com]] |access-date=2016-01-20 }}}} {{respell|SOR|ə|POD|ə|MOR|fə}}; from Greek, meaning "lizard-footed forms") is an extinct [[clade]] of long-necked, [[herbivorous]], [[saurischian]] dinosaurs that includes the [[Sauropoda|sauropod]]s and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were [[quadruped]]al, and became the largest animals to ever walk the Earth. The ''[[prosauropods]],'' which preceded the sauropods, were smaller and were often able to walk on two legs. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the [[Mesozoic Era]], from their origins in the [[Late Triassic]] (approximately 230 [[Myr|Ma]]) until their decline and extinction at the end of the [[Cretaceous]].


==Description==
==Description==
[[File:Nigersaurus taqueti skull.jpg|thumbnail|left|Skull of ''[[Nigersaurus taqueti]]'' and head posture in sauropodomorphs]]
[[File:Nigersaurus taqueti skull.jpg|thumbnail|left|Skull of ''[[Nigersaurus taqueti]]'' and head posture in sauropodomorphs]]
Sauropodomorphs were adapted to browsing higher than any other contemporary herbivore, giving them access to high [[tree]] [[foliage]]. This feeding strategy is supported by many of their defining characteristics, such as: a light, tiny [[skull]] on the end of a long [[neck]] (with ten or more elongated cervical [[vertebra]]e) and a counterbalancing long [[tail]] (with one to three extra sacral vertebrae).
Sauropodomorphs were adapted to browsing higher than any other contemporary herbivore, giving them access to high tree foliage. This feeding strategy is supported by many of their defining characteristics, such as: a light, tiny skull on the end of a long neck (with ten or more elongated cervical [[vertebra]]e) and a counterbalancing long tail (with one to three extra sacral vertebrae).{{citation needed|date=May 2024}}


Their [[teeth]] were weak, and shaped like leaves or spoons (lanceolate or spatulate). Instead of grinding teeth, they had stomach stones ([[gastrolith]]s), similar to the [[gizzard]] stones of [[montul]] [[bird]]s and [[crocodile]]s, to help digest tough plant fibers. The front of the upper mouth bends down in what may be a [[beak]].
Their teeth were weak, and shaped like leaves or spoons (lanceolate or spatulate). Instead of grinding teeth, they had stomach stones ([[gastrolith]]s), similar to the [[gizzard]] stones of birds and crocodiles, to help digest tough plant fibers. The front of the upper mouth bends down in what may be a beak.{{citation needed|date=May 2024}}


One of the earliest known sauropodomorphs, ''[[Saturnalia (dinosaur)|Saturnalia]]'', was small and slender (1.5&nbsp;metres, or 5&nbsp;feet long); but, by the end of the Triassic, they were the largest dinosaurs of their time, and throughout the [[Jurassic]] and [[Cretaceous]] they kept on growing. Ultimately the largest sauropods, like ''[[Supersaurus]]'', ''[[Diplodocus|Diplodocus hallorum]]'', ''[[Patagotitan]]'', and ''[[Argentinosaurus]]'', reached {{convert|30|-|40|m}} in length, and 60,000–100,000&nbsp;[[kilograms]] (65&ndash;110&nbsp;US [[short ton]]s) or more in mass.
One of the earliest known sauropodomorphs, ''[[Saturnalia (dinosaur)|Saturnalia]]'', was small and slender (1.5&nbsp;metres, or 5&nbsp;feet long); but, by the end of the Triassic, they were the largest dinosaurs of their time, and throughout the [[Jurassic]] and [[Cretaceous]] they kept on growing. Ultimately the largest sauropods, like ''[[Supersaurus]]'', ''[[Diplodocus|Diplodocus hallorum]]'', ''[[Patagotitan]]'', and ''[[Argentinosaurus]]'', reached {{convert|30|-|40|m}} in length, and 60,000–100,000&nbsp;[[kilograms]] (65&ndash;110&nbsp;US [[short ton]]s) or more in mass.{{citation needed|date=May 2024}}


Initially [[biped]]al, as their size increased they evolved a [[quadruped|four-legged]] [[wikt:graviportal|graviportal]] gait adapted only to walking slowly on land, like [[elephant]]s. The early sauropodomorphs were most likely [[omnivore]]s as their shared common ancestor with the other [[saurischia]]n lineage (the [[theropod]]s) was a [[carnivore]]. Therefore, their evolution to herbivory went hand in hand with their increasing size and neck length.
Initially [[biped]]al, as their size increased they evolved a [[quadruped|four-legged]] [[wikt:graviportal|graviportal]] gait adapted only to walking slowly on land, like elephants. The early sauropodomorphs were most likely [[omnivore]]s as their shared common ancestor with the other [[saurischia]]n lineage (the [[theropod]]s) was a [[carnivore]]. Therefore, their evolution to herbivory went hand in hand with their increasing size and neck length.{{citation needed|date=May 2024}}


They also had large [[nostril]]s (nares), and retained a [[thumb]] (pollex) with a big [[claw]], which may have been used for defense &mdash; though their primary defensive adaptation was their extreme size.
They also had large nostrils (nares), and retained a thumb (pollex) with a big claw, which may have been used for defense &mdash; though their primary defensive adaptation was their extreme size.{{citation needed|date=May 2024}}


===Distinguishing anatomical features===
===Distinguishing anatomical features===
Sauropodomorphs can be distinguished as a group on the basis of some of the following [[synapomorphies]]:<ref>Martin, A.J. (2006). Introduction to the Study of Dinosaurs. Second Edition. Oxford, Blackwell Publishing. pg. 299-300. {{ISBN|1-4051-3413-5}}.</ref>
Sauropodomorphs can be distinguished as a group on the basis of some of the following [[synapomorphies]]:<ref>Martin, A.J. (2006). Introduction to the Study of Dinosaurs. Second Edition. Oxford, Blackwell Publishing. pg. 299-300. {{ISBN|1-4051-3413-5}}.</ref>
* The presence of large nares.
* The presence of large nares.
* The distal part of the [[tibia]] is covered by an ascending process of the [[astragalus]].
* The distal part of the [[tibia]] is covered by an ascending process of the [[Talus bone|astragalus]].
* Their hind limbs are short when compared to their torso length.
* Their hind limbs are short when compared to their torso length.
* The presence of three or more sacral vertebrae.
* The presence of three or more sacral vertebrae.
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==Evolutionary history==
==Evolutionary history==
Among the first dinosaurs to evolve in the [[Late Triassic]] [[Period (geology)|Period]],<ref>{{Cite journal|last1=Müller|first1=Rodrigo T.|last2=Garcia|first2=Maurício S.|date=2019-03-08|title=Rise of an empire: analysing the high diversity of the earliest sauropodomorph dinosaurs through distinct hypotheses|journal=Historical Biology|volume=32|issue=10|language=en|pages=1334–1339|doi=10.1080/08912963.2019.1587754|s2cid=92177386|issn=0891-2963}}</ref> about 230 million years ago (Mya), they became the dominant herbivores by halfway through the late Triassic (during the [[Norian]] stage). Their perceived decline in the early [[Cretaceous]] is most likely a bias in fossil sampling, as most fossils are known from Europe and North America, but sauropods were still the dominant herbivores in the [[Gondwana]]n landmasses. The spread of [[flowering plant]]s (angiosperms) and "advanced" [[ornithischia]]ns, another major group of herbivorous dinosaurs (noted for their highly developed chewing mechanisms), are most likely not a major factor in sauropod decline in the northern continents{{citation needed|date=February 2015}}. Like all non-[[bird|avian]] dinosaurs, the sauropodomorphs became extinct 66 Mya, during the [[Cretaceous–Paleogene extinction event]].
Among the first dinosaurs to evolve in the Late Triassic period,<ref>{{Cite journal|last1=Müller|first1=Rodrigo T.|last2=Garcia|first2=Maurício S.|date=2019-03-08|title=Rise of an empire: analysing the high diversity of the earliest sauropodomorph dinosaurs through distinct hypotheses|journal=Historical Biology|volume=32|issue=10|language=en|pages=1334–1339|doi=10.1080/08912963.2019.1587754|s2cid=92177386|issn=0891-2963}}</ref> about 230 million years ago (Mya), they became the dominant herbivores by halfway through the late Triassic (during the [[Norian]] stage). Their perceived decline in the early Cretaceous is most likely a bias in fossil sampling, as most fossils are known from Europe and North America, but sauropods were still the dominant herbivores in the [[Gondwana]]n landmasses. The spread of [[flowering plant]]s (angiosperms) and "advanced" [[ornithischia]]ns, another major group of herbivorous dinosaurs (noted for their highly developed chewing mechanisms), are most likely not a major factor in sauropod decline in the northern continents{{citation needed|date=February 2015}}. Like all non-avian dinosaurs (birds), the sauropodomorphs became extinct 66 Mya, during the [[Cretaceous–Paleogene extinction event]].


The earliest and most [[Basal (phylogenetics)|basal]] sauropodomorphs known are ''[[Chromogisaurus novasi]]'' and ''[[Panphagia protos]]'', both from the [[Ischigualasto Formation]], dated to 231.4 million years ago (late [[Carnian]] age of the [[Late Triassic]] according to the [[International Commission on Stratigraphy|ICS]]<ref name=leal2004>{{cite journal | title = A new early dinosaur (Sauropodomorpha) from the Caturrita Formation (Late Triassic), Paraná Basin, Brazil | author= Luciano A. Leal | author2= Sergio A. K. Azevodo | author3= Alexander W. A. Kellner | author4= Átila A. S. da Rosa | name-list-style= amp | date = October 18, 2004 | journal = Zootaxa | volume = 690 | pages = 1–24 | url = http://www.mapress.com/zootaxa/2004f/z00690f.pdf | doi= 10.11646/zootaxa.690.1.1 }} (''Warning:'' abstract is 12 kb [[portable document format|PDF]])</ref><ref name=RMOA09>{{cite journal |last=Martínez |first=Ricardo N. |author2=Alcober, Oscar A. |year=2009 |title=A basal sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the early evolution of Sauropodomorpha |journal=PLOS ONE |volume=4 |issue=2 |pages=1–12|doi=10.1371/journal.pone.0004397 |pmid=19209223 |pmc=2635939 |editor1-last=Sereno |editor1-first=Paul|bibcode=2009PLoSO...4.4397M |doi-access=free }}</ref>). Some studies have found ''[[Eoraptor lunensis]]'' (also from the Ischigualasto Formation), traditionally considered a [[theropod]], to be an early member of the sauropodomorph lineage, which would make it the most basal sauropodomorph known.<ref name="Martinez2011">{{Cite journal|author=Ricardo N. Martinez|author2=Paul C. Sereno|author3=Oscar A. Alcober|author4=Carina E. Colombi|author5=Paul R. Renne|author6=Isabel P. Montañez|author7=Brian S. Currie|name-list-style=amp |year=2011 |title=A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea |url=https://www.science.org/doi/abs/10.1126/science.1198467 |journal=Science |volume=331 |issue=6014 |pages=206–210 |doi=10.1126/science.1198467 |pmid=21233386|bibcode=2011Sci...331..206M |s2cid=33506648}}</ref>
The earliest and most [[Basal (phylogenetics)|basal]] sauropodomorphs known are ''[[Chromogisaurus novasi]]'' and ''[[Panphagia protos]]'', both from the [[Ischigualasto Formation]], dated to 231.4 million years ago (late [[Carnian]] age of the Late Triassic according to the [[International Commission on Stratigraphy|ICS]]<ref name=leal2004>{{cite journal | title = A new early dinosaur (Sauropodomorpha) from the Caturrita Formation (Late Triassic), Paraná Basin, Brazil | author= Luciano A. Leal | author2= Sergio A. K. Azevodo | author3= Alexander W. A. Kellner | author4= Átila A. S. da Rosa | name-list-style= amp | date = October 18, 2004 | journal = Zootaxa | volume = 690 | pages = 1–24 | url = http://www.mapress.com/zootaxa/2004f/z00690f.pdf | doi= 10.11646/zootaxa.690.1.1 }} (''Warning:'' abstract is 12 kb [[portable document format|PDF]])</ref><ref name=RMOA09>{{cite journal |last=Martínez |first=Ricardo N. |author2=Alcober, Oscar A. |year=2009 |title=A basal sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the early evolution of Sauropodomorpha |journal=PLOS ONE |volume=4 |issue=2 |pages=1–12|doi=10.1371/journal.pone.0004397 |pmid=19209223 |pmc=2635939 |editor1-last=Sereno |editor1-first=Paul|bibcode=2009PLoSO...4.4397M |doi-access=free }}</ref>). Some studies have found ''[[Eoraptor lunensis]]'' (also from the Ischigualasto Formation), traditionally considered a theropod, to be an early member of the sauropodomorph lineage, which would make it the most basal sauropodomorph known.<ref name="Martinez2011">{{Cite journal|author=Ricardo N. Martinez|author2=Paul C. Sereno|author3=Oscar A. Alcober|author4=Carina E. Colombi|author5=Paul R. Renne|author6=Isabel P. Montañez|author7=Brian S. Currie|name-list-style=amp |year=2011 |title=A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea |url=https://www.science.org/doi/abs/10.1126/science.1198467 |journal=Science |volume=331 |issue=6014 |pages=206–210 |doi=10.1126/science.1198467 |pmid=21233386|bibcode=2011Sci...331..206M |s2cid=33506648|hdl=11336/69202 |hdl-access=free }}</ref>


==Classification==
==Classification==
[[File:Panphagia NT.jpg|thumb|Restoration of ''[[Panphagia]]'', one of the most basal sauropodomorphs known.]]
[[File:Panphagia NT.jpg|thumb|Restoration of ''[[Panphagia]]'', one of the most basal sauropodomorphs known.]]
[[File:Sellosaurus.jpg|thumb|''[[Plateosaurus]]'' is a well-known prosauropod.]]
[[File:Sellosaurus.jpg|thumb|''[[Plateosaurus]]'' is a well-known prosauropod.]]
Sauropodomorpha is one of the two major [[clade]]s within the [[order (biology)|order]] [[Saurischia]]. The sauropodomorphs' sister group, the [[Theropoda]], includes bipedal carnivores like ''[[Velociraptor]]'' and ''[[Tyrannosaurus]]''; as well as [[bird]]s. However, sauropodomorphs also share a number of characteristics with the [[Ornithischia]], so a small minority of [[palaeontologist]]s, like [[Robert Bakker|Bakker]], have historically placed both sets of herbivores within a group called "Phytodinosauria" or "Ornithischiformes".
Sauropodomorpha is one of the two major clades within the order [[Saurischia]]. The sauropodomorphs' sister group, the [[Theropoda]], includes bipedal carnivores like ''[[Velociraptor]]'' and ''[[Tyrannosaurus]]''; as well as birds. However, sauropodomorphs also share a number of characteristics with the [[Ornithischia]], so a small minority of [[palaeontologist]]s, like [[Robert Bakker|Bakker]], have historically placed both sets of herbivores within a group called "Phytodinosauria" or "Ornithischiformes".{{citation needed|date=June 2024}}


In [[Linnaean taxonomy]], Sauropodomorpha (which means "[[lizard]] feet forms") is either a [[suborder]] or is left unranked. It was originally established by [[Friedrich von Huene]] in 1932, who broke it into two groups: the basal forms within [[Prosauropoda]], and their descendants, the giant [[Sauropoda]].
In [[Linnaean taxonomy]], Sauropodomorpha (which means "lizard feet forms") is either a [[suborder]] or is left unranked. It was originally established by [[Friedrich von Huene]] in 1932, who broke it into two groups: the basal forms within [[Prosauropoda]], and their descendants, the giant [[Sauropoda]].{{citation needed|date=June 2024}}


[[Phylogenetic]] analyses by Adam Yates (2004, 2006) and others firmly placed Sauropoda within a [[paraphyletic]] "Prosauropoda". Recent [[cladistics|cladistic]] analyses suggest that the clade [[Prosauropoda]], which was named by Huene in 1920 and was defined by Sereno, in 1998, as all animals more closely related to ''[[Plateosaurus engelhardti]]'' than to ''[[Saltasaurus loricatus]]'',<ref name="sereno1998">{{cite journal | last1 = Sereno | first1 = P.C. | year = 1998 | title = A rationale for phylogenetic definitions, with applications to the higher-level taxonomy of Dinosauria | journal = Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen | volume = 210 | pages = 41–83 | doi=10.1127/njgpa/210/1998/41}}</ref> is a [[junior synonym]] of [[Plateosauridae]] as both contain the same taxa.<ref name=Y07>{{cite journal | last1 = Yates | first1 = Adam M. | year = 2007 | title = The first complete skull of the Triassic dinosaur ''Melanorosaurus'' Haughton (Sauropodomorpha: Anchisauria) |editor-first1= Paul M.|editor-last1=Barrett|editor-first2=David J.|editor-last2=Batten| journal = Evolution and Palaeobiology | pages = 9–55 }}</ref><ref name=Indiansaupo/>
[[Phylogenetic]] analyses by Adam Yates (2004, 2006) and others firmly placed Sauropoda within a [[paraphyletic]] "Prosauropoda". Recent cladistic analyses suggest that the clade [[Prosauropoda]], which was named by Huene in 1920 and was defined by Sereno, in 1998, as all animals more closely related to ''[[Plateosaurus engelhardti]]'' than to ''[[Saltasaurus loricatus]]'',<ref name="sereno1998">{{cite journal | last1 = Sereno | first1 = P.C. | year = 1998 | title = A rationale for phylogenetic definitions, with applications to the higher-level taxonomy of Dinosauria | journal = Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen | volume = 210 | pages = 41–83 | doi=10.1127/njgpa/210/1998/41}}</ref> is a junior synonym of [[Plateosauridae]] as both contain the same taxa.<ref name=Y07 /><ref name=Indiansaupo/>


Most modern classification schemes break the prosauropods into a half-dozen groups that evolved separately from one common lineage. While they have a number of shared characteristics, the [[evolution]]ary requirements for [[giraffe]]-like browsing high in the trees may have caused [[convergent evolution]], where similar traits evolve separately because they faced the same evolutionary pressure, instead of ([[homology (biology)|homologous]]) traits derived from a shared ancestor.<ref name=poletal2011>{{cite journal | author = Pol D. | author2 = Garrido A. | author3 = Cerda I.A. | year = 2011 | title = A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum | journal = PLOS ONE | volume = 6 | issue = 1| page = e14572 | doi = 10.1371/journal.pone.0014572 | pmid=21298087 | pmc=3027623 | editor1-last = Farke | editor1-first = Andrew Allen| bibcode = 2011PLoSO...614572P | doi-access = free }}</ref>
Most modern classification schemes break the prosauropods into a half-dozen groups that evolved separately from one common lineage. While they have a number of shared characteristics, the evolutionary requirements for giraffe-like browsing high in the trees may have caused [[convergent evolution]], where similar traits evolve separately because they faced the same evolutionary pressure, instead of ([[homology (biology)|homologous]]) traits derived from a shared ancestor.<ref name=poletal2011>{{cite journal | author = Pol D. | author2 = Garrido A. | author3 = Cerda I.A. | year = 2011 | title = A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum | journal = PLOS ONE | volume = 6 | issue = 1| page = e14572 | doi = 10.1371/journal.pone.0014572 | pmid=21298087 | pmc=3027623 | editor1-last = Farke | editor1-first = Andrew Allen| bibcode = 2011PLoSO...614572P | doi-access = free }}</ref>

⚫
The phylogenetic analysis of Otero et al., 2015 found Sauropodomorpha to be in a polytomy with ''[[Agnosphitys]]'' and [[Theropoda]] within [[Eusaurischia]], with [[Herrerasauridae]] and ''[[Eoraptor]]'' external to it within [[Saurischia]].<ref name="otero">{{cite journal|doi=10.1111/zoj.12247|title=A new basal sauropodiform from South Africa and the phylogenetic relationships of basal sauropodomorphs|journal=[[Zoological Journal of the Linnean Society]]|volume=174|issue=3|pages=589|year=2015|last1=Otero|first1=Alejandro|last2=Krupandan|first2=Emil|last3=Pol|first3=Diego|last4=Chinsamy|first4=Anusuya|last5=Choiniere|first5=Jonah|doi-access=free|hdl=11336/38019|hdl-access=free}}</ref> A large phylogenetic analysis of early dinosaurs published by Matthew Baron, [[David B. Norman|David Norman]] and Paul Barrett (2017) in the journal [[Nature (journal)|''Nature'']] redefined Sauropodomorpha and [[Saurischia]] and recovered [[Herrerasauridae]] as the [[sister group]] to Sauropodomorpha within Saurischia. This resulted from the proposed removal of [[Theropoda]] from Saurischia and the formation of [[Ornithoscelida]], a clade containing Theropoda and [[Ornithischia]].<ref name="Ornithoscelida">{{cite journal | last1 = Baron | first1 = M.G. | last2 = Norman | first2 = D.B. | last3 = Barrett | first3 = P.M. | year = 2017 | title = A new hypothesis of dinosaur relationships and early dinosaur evolution | journal = Nature | volume = 543 | issue = 7646| pages = 501–506 | doi = 10.1038/nature21700 | pmid = 28332513 | bibcode = 2017Natur.543..501B | s2cid = 205254710 }}</ref>


===Phylogeny===
===Phylogeny===
[[File:Sauropodomorpha skull comparison.jpg|thumb|right|Skull comparison of several sauropodomorphs]]
[[File:Sauropodomorpha skull comparison.jpg|thumb|right|Skull comparison of several sauropodomorphs]]
Within Sauropodomorpha, there is a large clade named '''Plateosauria'''. The name Plateosauria was first coined by [[Gustav Tornier]] in 1913.<ref>Tornier, G., 1913, "Reptilia (Paläontologie)" In: ''Handwörterbuch Naturwissenschaften'' '''8''': 337-376</ref> The name afterwards fell out of use until the 1980s. Plateosauria is a [[node-based taxon]]. In 1998, [[Paul Sereno]] defined Plateosauria as the [[last common ancestor]] of ''[[Plateosaurus engelhardti]]'' and ''[[Massospondylus carinatus]]'', and its descendants.<ref name="sereno1998" /> [[Peter Galton]] and [[Paul Upchurch]] in 2004 used a different definition: the last common ancestor of ''Plateosaurus engelhardti'' and ''[[Jingshanosaurus xinwaensis]]'', and its descendants. In their [[cladistic]] analysis the Plateosauria belonged to the Prosauropoda, and included the [[Plateosauridae]] subgroup. In Galton's and Upchurch's study also ''[[Coloradisaurus]]'', ''[[Euskelosaurus]]'', ''[[Jingshanosaurus]]'', ''[[Massospondylus]]'', ''[[Mussaurus]]'', ''[[Sellosaurus]]'', and ''[[Yunnanosaurus]]'' proved to be plateosaurians.<ref name=GU04>{{Cite journal|author1=Galton, P.M |author2=Upchurch, P. |name-list-style=amp |year=2004 |title=Prosauropoda |journal=In D. B. Weishampel, P. Dodson, & H. Osmólska (Eds.), the Dinosauria (Second edition). University of California Press, Berkeley |pages=232–258 }}</ref>
Cladogram after [[Fernando E. Novas|Novas]] ''et al.'', 2011:<ref name=Indiansaupo>{{Cite journal|author=Fernando E. Novas|author2=Martin D. Ezcurra|author3=Sankar Chatterjee|author4=T. S. Kutty|name-list-style=amp |year=2011 |title=New dinosaur species from the Upper Triassic Upper Maleri and Lower Dharmaram formations of central India |journal=Earth and Environmental Science Transactions of the Royal Society of Edinburgh |volume=101 |issue=3–4 |pages=333–349 |doi=10.1017/S1755691011020093|s2cid=128620874}}</ref>

However, recent [[cladistics|cladistic]] analyses suggest that the Prosauropoda as traditionally defined is [[paraphyletic]] to [[sauropod]]s.<ref name=Y03>{{cite journal | last1 = Yates | first1 = Adam M. | year = 2003 | title = Species taxonomy of the sauropodomorph dinosaurs from the Löwenstein Formation (Norian, Late Triassic) of Germany | journal = Palaeontology | volume = 46 | issue = 2 | pages = 317–337 | doi=10.1111/j.0031-0239.2003.00301.x| s2cid = 86801904 | doi-access = free }}</ref><ref name=Y07>{{cite journal | last1 = Yates | first1 = Adam M. | year = 2007 | title = The first complete skull of the Triassic dinosaur ''Melanorosaurus'' Haughton (Sauropodomorpha: Anchisauria) |editor-first1= Paul M.|editor-last1=Barrett|editor-first2=David J.|editor-last2=Batten| journal = Evolution and Palaeobiology | volume = 77 | pages = 9–55 | isbn = 978-1-4051-6933-2 }}</ref><ref name=poletal2011 /><ref name=Indiansaupo>{{Cite journal|author1=Fernando E. Novas |author2=Martin D. Ezcurra |author3=Sankar Chatterjee |author4=T. S. Kutty |year=2011 |title=New dinosaur species from the Upper Triassic Upper Maleri and Lower Dharmaram formations of central India |journal=Earth and Environmental Science Transactions of the Royal Society of Edinburgh |volume=101 |issue=3–4 |pages=333–349 |doi=10.1017/S1755691011020093|s2cid=128620874 }}</ref><ref name=Leyesaurus>{{cite journal |author1=Cecilia Apaldetti |author2=Ricardo N. Martinez |author3=Oscar A. Alcober |author4=Diego Pol |year=2011 |title=A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina |journal=PLOS ONE |volume=6 |issue=11 |pages=e26964 |doi=10.1371/journal.pone.0026964 |bibcode = 2011PLoSO...626964A |pmid=22096511 |pmc=3212523|doi-access=free }}</ref> Prosauropoda, as currently defined, is a [[synonym (taxonomy)|synonym]] of [[Plateosauridae]] as both contain the same taxa by definition. The phylogenetic analysis of 2021 recovered ''[[Issi]]'' and ''[[Plateosaurus]]'' as the basal-most plateosaurs.<ref>{{Cite journal|last1=Beccari|first1=Victor|last2=Mateus|first2=Octávio|last3=Wings|first3=Oliver|last4=Milàn|first4=Jesper|last5=Clemmensen|first5=Lars B.|date=November 2021|title=Issi saaneq gen. et sp. nov.—A New Sauropodomorph Dinosaur from the Late Triassic (Norian) of Jameson Land, Central East Greenland|journal=Diversity|language=en|volume=13|issue=11|pages=561|doi=10.3390/d13110561|doi-access=free|hdl=10362/128951|hdl-access=free}}</ref>

Cladogram after [[Fernando E. Novas|Novas]] et al., 2011:<ref name=Indiansaupo />


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|2=[[Massospondylidae]] }} }} }} }} }} }} }} }} }} }} }}
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⚫
Below is a cladogram of basal sauropodomorpha after Müller, 2019.<ref name="Muller2019">{{Cite journal |doi = 10.1080/14772019.2019.1683902|title = Craniomandibular osteology of ''Macrocollum itaquii'' (Dinosauria: Sauropodomorpha) from the Late Triassic of southern Brazil|journal = Journal of Systematic Palaeontology|pages = 805–841|year = 2019|last1 = Müller|first1 = Rodrigo Temp|volume = 18|issue = 10|s2cid = 209575985}}</ref>
⚫
The phylogenetic analysis of Otero ''et al.'', 2015 found Sauropodomorpha to be in a polytomy with ''[[Agnosphitys]]'' and [[Theropoda]] within [[Eusaurischia]], with [[Herrerasauridae]] and ''[[Eoraptor]]'' external to it within [[Saurischia]].<ref name="otero">{{cite journal|doi=10.1111/zoj.12247|title=A new basal sauropodiform from South Africa and the phylogenetic relationships of basal sauropodomorphs|journal=[[Zoological Journal of the Linnean Society]]|volume=174|issue=3|pages=589|year=2015|last1=Otero|first1=Alejandro|last2=Krupandan|first2=Emil|last3=Pol|first3=Diego|last4=Chinsamy|first4=Anusuya|last5=Choiniere|first5=Jonah|doi-access=free}}</ref> A large phylogenetic analysis of early dinosaurs published by Matthew Baron, [[David B. Norman|David Norman]] and Paul Barrett (2017) in the journal [[Nature (journal)|''Nature'']] redefined Sauropodomorpha and [[Saurischia]] and recovered [[Herrerasauridae]] as the [[sister group]] to Sauropodomorpha within Saurischia. This resulted from the proposed removal of [[Theropoda]] from Saurischia and the formation of [[Ornithoscelida]], a clade containing Theropoda and [[Ornithischia]].<ref name="Ornithoscelida">{{cite journal | last1 = Baron | first1 = M.G. | last2 = Norman | first2 = D.B. | last3 = Barrett | first3 = P.M. | year = 2017 | title = A new hypothesis of dinosaur relationships and early dinosaur evolution | journal = Nature | volume = 543 | issue = 7646| pages = 501–506 | doi = 10.1038/nature21700 | pmid = 28332513 | bibcode = 2017Natur.543..501B | s2cid = 205254710 }}</ref>

⚫
Below is a cladogram of basal sauropodomorpha after Müller, 2019.<ref name="Muller2019">{{Cite journal |doi = 10.1080/14772019.2019.1683902|title = Craniomandibular osteology of Macrocollum itaquii (Dinosauria: Sauropodomorpha) from the Late Triassic of southern Brazil|journal = Journal of Systematic Palaeontology|pages = 805–841|year = 2019|last1 = Müller|first1 = Rodrigo Temp|volume = 18|issue = 10|s2cid = 209575985}}</ref>


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==Paleobiology==
==Paleobiology==
Comparisons between the [[sclerotic ring|scleral ring]]s of several sauropodomorph genera (''[[Diplodocus]]'', ''[[Lufengosaurus]]'', ''[[Nemegtosaurus]]'', ''[[Plateosaurus]]'', and ''[[Riojasaurus]]'') and modern birds and reptiles suggest that they may have been [[cathemeral]], active throughout the day at short intervals.<ref>{{cite journal|author1=Schmitz, L. |author2=Motani, R. |year=2011 |title=Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology |journal=Science |volume = →→→§332 |issue= 6030|pages= 705–8|doi=10.1126/science.1200043 |pmid=21493820|bibcode=2011Sci...332..705S |s2cid=33253407 |url=https://semanticscholar.org/paper/8922c462d9cd7f64033fe9989f5a1dc0e7e8aac9 }}</ref>
Comparisons between the [[sclerotic ring|scleral ring]]s of several sauropodomorph genera (''[[Diplodocus]]'', ''[[Lufengosaurus]]'', ''[[Nemegtosaurus]]'', ''[[Plateosaurus]]'', and ''[[Riojasaurus]]'') and modern birds and reptiles suggest that they may have been [[cathemeral]], active throughout the day at short intervals.<ref>{{cite journal|author1=Schmitz, L. |author2=Motani, R. |year=2011 |title=Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology |journal=Science |volume = →→→§332 |issue= 6030|pages= 705–8|doi=10.1126/science.1200043 |pmid=21493820|bibcode=2011Sci...332..705S |s2cid=33253407 }}</ref>


Sauropodomorphs reached the age of sexual maturity well before they were fully-grown adults.<ref>{{cite journal | last1 = Sander | first1 = PM | year = 2000 | title = Long bone histology of the Tendaguru sauropods: implications for growth and biology | journal = Paleobiology | volume = 26 | issue = 3| pages = 466–488 | doi = 10.1666/0094-8373(2000)026<0466:lhotts>2.0.co;2 }}</ref><ref name=Griebeler13>{{cite journal | last1 = Griebeler | first1 = EM | last2 = Klein | first2 = N | last3 = Sander | first3 = PM | year = 2013 | title = Aging, Maturation and Growth of Sauropodomorph Dinosaurs as Deduced from Growth Curves Using Long Bone Histological Data: An Assessment of Methodological Constraints and Solutions | journal = PLOS ONE | volume = 8 | issue = 6| page = e67012 | doi = 10.1371/journal.pone.0067012 | pmid = 23840575 | pmc = 3686781 | bibcode = 2013PLoSO...867012G | doi-access = free }}</ref> A study by Griebeler ''et al.'' (2013) concluded that the maximum growth rates of sauropodomorphs were comparable to those of precocial birds and the black rhinoceros but lower than the growth rates of average mammals.<ref name=Griebeler13/>
Sauropodomorphs reached the age of sexual maturity well before they were fully-grown adults.<ref>{{cite journal | last1 = Sander | first1 = PM | year = 2000 | title = Long bone histology of the Tendaguru sauropods: implications for growth and biology | journal = Paleobiology | volume = 26 | issue = 3| pages = 466–488 | doi = 10.1666/0094-8373(2000)026<0466:lhotts>2.0.co;2 | bibcode = 2000Pbio...26..466S | s2cid = 86183725 | url = http://doc.rero.ch/record/16668/files/PAL_E2877.pdf }}</ref><ref name=Griebeler13>{{cite journal | last1 = Griebeler | first1 = EM | last2 = Klein | first2 = N | last3 = Sander | first3 = PM | year = 2013 | title = Aging, Maturation and Growth of Sauropodomorph Dinosaurs as Deduced from Growth Curves Using Long Bone Histological Data: An Assessment of Methodological Constraints and Solutions | journal = PLOS ONE | volume = 8 | issue = 6| page = e67012 | doi = 10.1371/journal.pone.0067012 | pmid = 23840575 | pmc = 3686781 | bibcode = 2013PLoSO...867012G | doi-access = free }}</ref> A study by Griebeler et al. (2013) concluded that the maximum growth rates of sauropodomorphs were comparable to those of precocial birds and the black rhinoceros but lower than the growth rates of average mammals.<ref name=Griebeler13/>


A long-standing hypothesis has been that early sauropodomorphs were carnivorous, as expected for most early dinosaurs. This hypothesis is supported by the current basalmost sauropodomorph, ''[[Buriolestes]]'', and its [[symplesiomorphy|plesiomorphic]], theropod-like teeth.<ref name="cabreira2016">{{cite journal | first1 = S.F. | last1 = Cabreira | first2 = A.W.A. | last2 = Kellner | first3 = S. | last3 = Dias-da-Silva | first4 = L.R. | last4 = da Silva | first5 = M. | last5 = Bronzati | first6 = J.C. | last6 = de Almeida Marsala | first7 = R.T. | last7 = Müller | first8 = J. | last8 = de Souza Bittencourt | first9 = B.J. | last9 = Batista | first10 = T. | last10 = Raugust | first11 = R. | last11 = Carrilho | first12 = A. | last12 = Brodt | first13 = M.C. | last13 = Langer | title = A Unique Late Triassic Dinosauromorph Assemblage Reveals Dinosaur Ancestral Anatomy and Diet | journal = Current Biology | doi = 10.1016/j.cub.2016.09.040 | pmid = 27839975 | date = 2016 | volume=26 | issue = 22 | pages=3090–3095| doi-access = free }}</ref> The teeth of more derived sauropodomorphs such as ''[[Eoraptor]]'', ''[[Panphagia]]'', and ''[[Pampadromaeus]]'' are better-suited for herbivorous (or possibly omnivorous) diets.<ref name=sereno13>{{cite journal | last1 = Sereno | first1 = Paul C. | last2 = Martínez | first2 = Ricardo N. | last3 = Alcober | first3 = Oscar A. | year = 2013 | title = Osteology of Eoraptor lunensis (Dinosauria, Sauropodomorph a). Basal sauropodomorphs and the vertebrate fossil record of the Ischigualasto Formation (Late Triassic: Carnian-Norian) of Argentina | journal = Journal of Vertebrate Paleontology Memoir | volume = 12 | pages = 83–179 | doi = 10.1080/02724634.2013.820113 | s2cid = 86006363 }}</ref> Regardless of the phylogenetic position of herrerasaurids or ''[[Eoraptor]]'' (which are in flux),<ref name=sereno13/><ref name=sues11>{{cite journal | last1 = Sues | first1 = Hans-Dieter | last2 = Nesbitt | first2 = Sterling J. | last3 = Berman | first3 = David S. | last4 = Henrici | first4 = Amy C. | year = 2011 | title = A late-surviving basal theropod dinosaur from the latest Triassic of North America | journal = Proceedings of the Royal Society B | volume = 278 | issue = 1723| pages = 3459–3464 | doi = 10.1098/rspb.2011.0410 | pmid = 21490016 | pmc = 3177637 }}</ref><ref name=theropodphylogeny2015>{{cite journal | last1 = Hendrickx | first1 = C. | last2 = Hartman | first2 = S.A. | last3 = Mateus | first3 = O. | year = 2015 | title = An Overview of Non- Avian Theropod Discoveries and Classification | journal = PalArch's Journal of Vertebrate Palaeontology | volume = 12 | issue = 1| pages = 1–73 }}</ref> ancestral state reconstructions recover carnivory as being ancestral to sauropodomorphs.<ref name="cabreira2016"/>
A long-standing hypothesis has been that early sauropodomorphs were carnivorous, as expected for most early dinosaurs. This hypothesis is supported by the current basalmost sauropodomorph, ''[[Buriolestes]]'', and its [[symplesiomorphy|plesiomorphic]], theropod-like teeth.<ref name="cabreira2016">{{cite journal | first1 = S.F. | last1 = Cabreira | first2 = A.W.A. | last2 = Kellner | first3 = S. | last3 = Dias-da-Silva | first4 = L.R. | last4 = da Silva | first5 = M. | last5 = Bronzati | first6 = J.C. | last6 = de Almeida Marsala | first7 = R.T. | last7 = Müller | first8 = J. | last8 = de Souza Bittencourt | first9 = B.J. | last9 = Batista | first10 = T. | last10 = Raugust | first11 = R. | last11 = Carrilho | first12 = A. | last12 = Brodt | first13 = M.C. | last13 = Langer | title = A Unique Late Triassic Dinosauromorph Assemblage Reveals Dinosaur Ancestral Anatomy and Diet | journal = Current Biology | doi = 10.1016/j.cub.2016.09.040 | pmid = 27839975 | date = 2016 | volume=26 | issue = 22 | pages=3090–3095| doi-access = free | bibcode = 2016CBio...26.3090C }}</ref> The teeth of more derived sauropodomorphs such as ''[[Eoraptor]]'', ''[[Panphagia]]'', and ''[[Pampadromaeus]]'' are better-suited for herbivorous (or possibly omnivorous) diets.<ref name=sereno13>{{cite journal | last1 = Sereno | first1 = Paul C. | last2 = Martínez | first2 = Ricardo N. | last3 = Alcober | first3 = Oscar A. | year = 2013 | title = Osteology of Eoraptor lunensis (Dinosauria, Sauropodomorph a). Basal sauropodomorphs and the vertebrate fossil record of the Ischigualasto Formation (Late Triassic: Carnian-Norian) of Argentina | journal = Journal of Vertebrate Paleontology Memoir | volume = 12 | pages = 83–179 | doi = 10.1080/02724634.2013.820113 | s2cid = 86006363 }}</ref> Regardless of the phylogenetic position of herrerasaurids or ''[[Eoraptor]]'' (which are in flux),<ref name=sereno13/><ref name=sues11>{{cite journal | last1 = Sues | first1 = Hans-Dieter | last2 = Nesbitt | first2 = Sterling J. | last3 = Berman | first3 = David S. | last4 = Henrici | first4 = Amy C. | year = 2011 | title = A late-surviving basal theropod dinosaur from the latest Triassic of North America | journal = Proceedings of the Royal Society B | volume = 278 | issue = 1723| pages = 3459–3464 | doi = 10.1098/rspb.2011.0410 | pmid = 21490016 | pmc = 3177637 }}</ref><ref name=theropodphylogeny2015>{{cite journal | last1 = Hendrickx | first1 = C. | last2 = Hartman | first2 = S.A. | last3 = Mateus | first3 = O. | year = 2015 | title = An Overview of Non- Avian Theropod Discoveries and Classification | journal = PalArch's Journal of Vertebrate Palaeontology | volume = 12 | issue = 1| pages = 1–73 }}</ref> ancestral state reconstructions recover carnivory as being ancestral to sauropodomorphs.<ref name="cabreira2016"/>


==References==
==References==
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==External links==
==External links==
* [https://web.archive.org/web/20050115161940/http://www.palaeos.com/vertebrates/Units/Unit330/330.000.html Sauropodomorpha: Overview], from Palæos.
* [https://web.archive.org/web/20050115161940/http://www.palaeos.com/vertebrates/Units/Unit330/330.000.html Sauropodomorpha: Overview], from Palæos.
* [http://users.tamuk.edu/kfjab02/dinos/VPSAUROPOD.htm Sauropodmorpha], from When Dinosaurs Ruled Texas, by Jon A. Baskin.
* [http://users.tamuk.edu/kfjab02/dinos/VPSAUROPOD.htm Sauropodmorpha] {{Webarchive|url=https://web.archive.org/web/20190702050521/http://users.tamuk.edu/kfjab02/dinos/VPSAUROPOD.htm |date=2019-07-02 }}, from When Dinosaurs Ruled Texas, by Jon A. Baskin.
* [http://www.geol.umd.edu/~tholtz/G104/10421saur.htm Geol 104 Dinosaurs: A natural history: Sauropodomorpha: Size matters], by [[Thomas R. Holtz Jr.]], from the University of Maryland.
* [http://www.geol.umd.edu/~tholtz/G104/10421saur.htm Geol 104 Dinosaurs: A natural history: Sauropodomorpha: Size matters], by [[Thomas R. Holtz Jr.]], from the University of Maryland.
* {{Wikispecies-inline|Sauropodomorpha}}
* {{Wikispecies-inline|Sauropodomorpha}}
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{{Sauropodomorpha|S.|state=autocollapse}}
{{Sauropodomorpha|S.|state=autocollapse}}
{{Portal bar|Dinosaurs|Paleontology|Mesozoic}}
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[[Category:Maastrichtian extinctions]]
[[Category:Maastrichtian extinctions]]
[[Category:Taxa named by Friedrich von Huene]]
[[Category:Taxa named by Friedrich von Huene]]
[[Category:Fossil taxa described in 1932]]
[[Category:Taxa described in 1932]]
[[Category:Dinosaur unranked clades]]

Latest revision as of 23:32, 27 July 2024

Sauropodomorphs
Temporal range: 233.23–66 Ma[1]
Six sauropodomorphs (top left to bottom right): Plateosaurus, Brontosaurus, Massospondylus, Eoraptor, Thecodontosaurus, Cetiosaurus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Eusaurischia
Clade: †Sauropodomorpha
Huene, 1932
Subgroups

Sauropodomorpha (/ˌsɔːrəˌpɒdəˈmɔːrfə/[2] SOR-ə-POD-ə-MOR-fə; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were quadrupedal, and became the largest animals to ever walk the Earth. The prosauropods, which preceded the sauropods, were smaller and were often able to walk on two legs. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the Mesozoic Era, from their origins in the Late Triassic (approximately 230 Ma) until their decline and extinction at the end of the Cretaceous.

Description

[edit]
Skull of Nigersaurus taqueti and head posture in sauropodomorphs

Sauropodomorphs were adapted to browsing higher than any other contemporary herbivore, giving them access to high tree foliage. This feeding strategy is supported by many of their defining characteristics, such as: a light, tiny skull on the end of a long neck (with ten or more elongated cervical vertebrae) and a counterbalancing long tail (with one to three extra sacral vertebrae).[citation needed]

Their teeth were weak, and shaped like leaves or spoons (lanceolate or spatulate). Instead of grinding teeth, they had stomach stones (gastroliths), similar to the gizzard stones of birds and crocodiles, to help digest tough plant fibers. The front of the upper mouth bends down in what may be a beak.[citation needed]

One of the earliest known sauropodomorphs, Saturnalia, was small and slender (1.5 metres, or 5 feet long); but, by the end of the Triassic, they were the largest dinosaurs of their time, and throughout the Jurassic and Cretaceous they kept on growing. Ultimately the largest sauropods, like Supersaurus, Diplodocus hallorum, Patagotitan, and Argentinosaurus, reached 30–40 metres (98–131 ft) in length, and 60,000–100,000 kilograms (65–110 US short tons) or more in mass.[citation needed]

Initially bipedal, as their size increased they evolved a four-legged graviportal gait adapted only to walking slowly on land, like elephants. The early sauropodomorphs were most likely omnivores as their shared common ancestor with the other saurischian lineage (the theropods) was a carnivore. Therefore, their evolution to herbivory went hand in hand with their increasing size and neck length.[citation needed]

They also had large nostrils (nares), and retained a thumb (pollex) with a big claw, which may have been used for defense — though their primary defensive adaptation was their extreme size.[citation needed]

Distinguishing anatomical features

[edit]

Sauropodomorphs can be distinguished as a group on the basis of some of the following synapomorphies:[3]

  • The presence of large nares.
  • The distal part of the tibia is covered by an ascending process of the astragalus.
  • Their hind limbs are short when compared to their torso length.
  • The presence of three or more sacral vertebrae.
  • The teeth are thin, flat and are spatula-like, with bladed and serrated crowns.
  • The presence of a minimum of 10 cervical vertebrae that are typically elongated
  • The presence of 25 presacral vertebrae
  • The manus had a large digit I.

Evolutionary history

[edit]

Among the first dinosaurs to evolve in the Late Triassic period,[4] about 230 million years ago (Mya), they became the dominant herbivores by halfway through the late Triassic (during the Norian stage). Their perceived decline in the early Cretaceous is most likely a bias in fossil sampling, as most fossils are known from Europe and North America, but sauropods were still the dominant herbivores in the Gondwanan landmasses. The spread of flowering plants (angiosperms) and "advanced" ornithischians, another major group of herbivorous dinosaurs (noted for their highly developed chewing mechanisms), are most likely not a major factor in sauropod decline in the northern continents[citation needed]. Like all non-avian dinosaurs (birds), the sauropodomorphs became extinct 66 Mya, during the Cretaceous–Paleogene extinction event.

The earliest and most basal sauropodomorphs known are Chromogisaurus novasi and Panphagia protos, both from the Ischigualasto Formation, dated to 231.4 million years ago (late Carnian age of the Late Triassic according to the ICS[5][6]). Some studies have found Eoraptor lunensis (also from the Ischigualasto Formation), traditionally considered a theropod, to be an early member of the sauropodomorph lineage, which would make it the most basal sauropodomorph known.[7]

Classification

[edit]
Restoration of Panphagia, one of the most basal sauropodomorphs known.
Plateosaurus is a well-known prosauropod.

Sauropodomorpha is one of the two major clades within the order Saurischia. The sauropodomorphs' sister group, the Theropoda, includes bipedal carnivores like Velociraptor and Tyrannosaurus; as well as birds. However, sauropodomorphs also share a number of characteristics with the Ornithischia, so a small minority of palaeontologists, like Bakker, have historically placed both sets of herbivores within a group called "Phytodinosauria" or "Ornithischiformes".[citation needed]

In Linnaean taxonomy, Sauropodomorpha (which means "lizard feet forms") is either a suborder or is left unranked. It was originally established by Friedrich von Huene in 1932, who broke it into two groups: the basal forms within Prosauropoda, and their descendants, the giant Sauropoda.[citation needed]

Phylogenetic analyses by Adam Yates (2004, 2006) and others firmly placed Sauropoda within a paraphyletic "Prosauropoda". Recent cladistic analyses suggest that the clade Prosauropoda, which was named by Huene in 1920 and was defined by Sereno, in 1998, as all animals more closely related to Plateosaurus engelhardti than to Saltasaurus loricatus,[8] is a junior synonym of Plateosauridae as both contain the same taxa.[9][10]

Most modern classification schemes break the prosauropods into a half-dozen groups that evolved separately from one common lineage. While they have a number of shared characteristics, the evolutionary requirements for giraffe-like browsing high in the trees may have caused convergent evolution, where similar traits evolve separately because they faced the same evolutionary pressure, instead of (homologous) traits derived from a shared ancestor.[11]

The phylogenetic analysis of Otero et al., 2015 found Sauropodomorpha to be in a polytomy with Agnosphitys and Theropoda within Eusaurischia, with Herrerasauridae and Eoraptor external to it within Saurischia.[12] A large phylogenetic analysis of early dinosaurs published by Matthew Baron, David Norman and Paul Barrett (2017) in the journal Nature redefined Sauropodomorpha and Saurischia and recovered Herrerasauridae as the sister group to Sauropodomorpha within Saurischia. This resulted from the proposed removal of Theropoda from Saurischia and the formation of Ornithoscelida, a clade containing Theropoda and Ornithischia.[13]

Phylogeny

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Skull comparison of several sauropodomorphs

Within Sauropodomorpha, there is a large clade named Plateosauria. The name Plateosauria was first coined by Gustav Tornier in 1913.[14] The name afterwards fell out of use until the 1980s. Plateosauria is a node-based taxon. In 1998, Paul Sereno defined Plateosauria as the last common ancestor of Plateosaurus engelhardti and Massospondylus carinatus, and its descendants.[8] Peter Galton and Paul Upchurch in 2004 used a different definition: the last common ancestor of Plateosaurus engelhardti and Jingshanosaurus xinwaensis, and its descendants. In their cladistic analysis the Plateosauria belonged to the Prosauropoda, and included the Plateosauridae subgroup. In Galton's and Upchurch's study also Coloradisaurus, Euskelosaurus, Jingshanosaurus, Massospondylus, Mussaurus, Sellosaurus, and Yunnanosaurus proved to be plateosaurians.[15]

However, recent cladistic analyses suggest that the Prosauropoda as traditionally defined is paraphyletic to sauropods.[16][9][11][10][17] Prosauropoda, as currently defined, is a synonym of Plateosauridae as both contain the same taxa by definition. The phylogenetic analysis of 2021 recovered Issi and Plateosaurus as the basal-most plateosaurs.[18]

Cladogram after Novas et al., 2011:[10]

Sauropodomorpha

Below is a cladogram of basal sauropodomorpha after Müller, 2019.[19]

Sauropodomorpha

Paleobiology

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Comparisons between the scleral rings of several sauropodomorph genera (Diplodocus, Lufengosaurus, Nemegtosaurus, Plateosaurus, and Riojasaurus) and modern birds and reptiles suggest that they may have been cathemeral, active throughout the day at short intervals.[20]

Sauropodomorphs reached the age of sexual maturity well before they were fully-grown adults.[21][22] A study by Griebeler et al. (2013) concluded that the maximum growth rates of sauropodomorphs were comparable to those of precocial birds and the black rhinoceros but lower than the growth rates of average mammals.[22]

A long-standing hypothesis has been that early sauropodomorphs were carnivorous, as expected for most early dinosaurs. This hypothesis is supported by the current basalmost sauropodomorph, Buriolestes, and its plesiomorphic, theropod-like teeth.[23] The teeth of more derived sauropodomorphs such as Eoraptor, Panphagia, and Pampadromaeus are better-suited for herbivorous (or possibly omnivorous) diets.[24] Regardless of the phylogenetic position of herrerasaurids or Eoraptor (which are in flux),[24][25][26] ancestral state reconstructions recover carnivory as being ancestral to sauropodomorphs.[23]

References

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  1. ^ Langer, M.C.; Ramezani, J.; Da Rosa, Á.A.S. (2018). "U-Pb age constraints on dinosaur rise from south Brazil". Gondwana Research. X (18): 133–140. Bibcode:2018GondR..57..133L. doi:10.1016/j.gr.2018.01.005.
  2. ^ Cf. "sauropodomorph - definition of sauropodomorph in English from the Oxford dictionary". OxfordDictionaries.com. Archived from the original on November 1, 2015. Retrieved 2016-01-20.
  3. ^ Martin, A.J. (2006). Introduction to the Study of Dinosaurs. Second Edition. Oxford, Blackwell Publishing. pg. 299-300. ISBN 1-4051-3413-5.
  4. ^ Müller, Rodrigo T.; Garcia, Maurício S. (2019-03-08). "Rise of an empire: analysing the high diversity of the earliest sauropodomorph dinosaurs through distinct hypotheses". Historical Biology. 32 (10): 1334–1339. doi:10.1080/08912963.2019.1587754. ISSN 0891-2963. S2CID 92177386.
  5. ^ Luciano A. Leal; Sergio A. K. Azevodo; Alexander W. A. Kellner & Átila A. S. da Rosa (October 18, 2004). "A new early dinosaur (Sauropodomorpha) from the Caturrita Formation (Late Triassic), Paraná Basin, Brazil" (PDF). Zootaxa. 690: 1–24. doi:10.11646/zootaxa.690.1.1. (Warning: abstract is 12 kb PDF)
  6. ^ Martínez, Ricardo N.; Alcober, Oscar A. (2009). Sereno, Paul (ed.). "A basal sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the early evolution of Sauropodomorpha". PLOS ONE. 4 (2): 1–12. Bibcode:2009PLoSO...4.4397M. doi:10.1371/journal.pone.0004397. PMC 2635939. PMID 19209223.
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  12. ^ Otero, Alejandro; Krupandan, Emil; Pol, Diego; Chinsamy, Anusuya; Choiniere, Jonah (2015). "A new basal sauropodiform from South Africa and the phylogenetic relationships of basal sauropodomorphs". Zoological Journal of the Linnean Society. 174 (3): 589. doi:10.1111/zoj.12247. hdl:11336/38019.
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Sources

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