Editing Eoraptor

{{Short description|Extinct genus of dinosaurs}}
{{distinguish|Egoraptor}}
{{Speciesbox
| fossil_range = [[Late Triassic]]  ([[Carnian]]),<ref name="OARM2010"/> {{fossil range|231|228}}
| image = Royal Ontario Museum Eoraptor.JPG
| image_caption = Reconstructed skeleton, [[Royal Ontario Museum]]
| display_parents = 2
| genus = Eoraptor
| parent_authority = [[Paul Sereno|Sereno]] ''et al.'' 1993
| species = lunensis
| authority = Sereno ''et al.'' 1993
}}

'''''Eoraptor''''' ({{IPAc-en|ˈ|iː|oʊ|ˌ|r|æ|p|t|ər}}) is a [[genus]] of small, lightly built, [[Basal (phylogenetics)|basal]] [[sauropodomorpha|sauropodomorph]] [[dinosaur]]. One of the earliest-known dinosaurs and one of the earliest sauropodomorphs, it lived approximately 231 to 228 [[million years ago]],<ref name="OARM2010">{{cite journal |last1=Alcober |first1=Oscar A. |last2=Martinez |first2=Ricardo N. |year=2010 |title=A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina |journal=ZooKeys |issue=63 |pages=55–81 |doi=10.3897/zookeys.63.550 |pmc=3088398 |pmid=21594020 |doi-access=free|bibcode=2010ZooK...63...55A }} [https://www.pensoft.net/inc/journals/download.php?fileId=1401&fileTable=J_GALLEYS] {{Webarchive|url=https://web.archive.org/web/20160313050125/http://www.pensoft.net/inc/journals/download.php?fileid=1401&filetable=j_galleys |date=2016-03-13 }}</ref> during the [[Late Triassic]] in Western [[Gondwana]], in the region that is now northwestern [[Argentina]]. The [[type species|type]] and only species, '''''Eoraptor lunensis''''', was first described in 1993, and is known from an almost complete and well-preserved skeleton and several fragmentary ones. ''Eoraptor'' had [[heterodont|multiple tooth shapes]], which suggests that it was [[omnivore|omnivorous]].

== History of discovery ==
[[File:Eoraptor fossil.jpg|thumb|Holotype specimen]] 
The bones of this primitive dinosaur were first discovered in 1991, by [[National University of San Juan|University of San Juan]] paleontologist Ricardo Martínez, during field work conducted by the [[University of Chicago]] and the University of San Juan. The [[holotype]] specimen ''PVSJ 512'' was discovered in muddy [[siltstone]] belonging to the Cancha de Bochas Member of the [[Ischigualasto Formation]] in Argentina. The fossils in this formation were deposited in the [[Carnian]] stage of the [[Triassic period]], approximately 235 to 228 million years ago. It took almost 12 months to collect the holotype,{{citation needed|date=March 2019}} which was then shipped to the [[Field Museum of Natural History]] in Chicago for preparation by William F. Simpson and Bob Masek. The fossil was first put on display in Chicago and was then returned to [[San Juan, Argentina]], where it went on display at the Museum of Natural Sciences.

[[File:Eoraptor1.JPG|thumb|left|Skull cast]]
The genus ''Eoraptor'' was described and named by [[Paul Sereno]], [[Catherine Forster]], [[Raymond R. Rogers]], and Alfredo M. Monetta in [[1993 in paleontology|1993]].<ref name=sereno93/> The name is derived from the Greek word {{lang|grc-Latn|eós}} ({{wikt-lang|grc|ἠώς}}) meaning 'dawn',<ref name="Liddell 1980">{{cite book |last1=Liddell |first1=Henry George |url=https://archive.org/details/lexicon00lidd |title=A Greek-English Lexicon |last2=Scott |first2=Robert |publisher=Oxford University Press |year=1980 |isbn=0-19-910207-4 |edition=Abridged |location=United Kingdom |author-link=Henry Liddell |author-link2=Robert Scott (philologist) |url-access=registration}}</ref> a reference to its primitive nature, and the Latin word {{wikt-lang|la|raptor}} meaning 'plunderer', a reference to its presumed carnivorous nature and its grasping hand. The [[specific name (zoology)|specific name]] ''lunensis'' is derived from the Latin words {{lang|la|luna}} ('moon') and the suffix {{wikt-lang|la|-ensis}} ('inhabitant'), a reference to its place of discovery: the {{lang|es|[[Ischigualasto Provincial Park|Valle de la Luna]]}} ('Valley of the Moon'), so named for its arid, otherworldly appearance evocative of a lunar landscape. The [[type species]] ''Eoraptor lunensis'' means 'dawn plunderer from the Valley of the Moon'.

== Description ==
[[File:Eoraptor Scale.svg|thumb|left|''Eoraptor'' compared in size to a human]] 
[[File:Eoraptor skeletal.png|left|thumb|Skeleton of ''Eoraptor lunensis'', known remains depicted in white and light grey, unknown in dark grey]]
''Eoraptor'' was a small dinosaur, with the known specimens measuring {{cvt|1.2|-|1.3|m|ft}} in length,<ref name=sereno13/> and weighing around or less than {{cvt|10|kg|lb}}.<ref>{{cite book|author1=Rauhut, O.W.M.|author2=Fechner, R.|author3=Remes, K.|author4=Reis, K.|year=2011|chapter=How to Get Big in the Mesozoic: The Evolution of the Sauropodomorph Body Plan|title=Biology of the Sauropod Dinosaurs: Understanding the Life of Giants|publisher=Indiana University Press|editor1=Klein, N.|editor2=Remes, K.|editor3=Sander, P.M.|pages=119–149|isbn=978-0253355089}}</ref> It had a lightly built skull with a slightly enlarged external [[Nostril|naris]].<ref name=sereno13/> As in early [[sauropodomorph]]s such as ''[[Buriolestes]]'' and ''[[Pampadromaeus]]'' and [[Coelophysoidea|coelophysoids]] (which would appear millions of years later), ''Eoraptor'' had a kink in its upper jaws, between the [[maxilla]] and the [[premaxilla]]. [[Paul Sereno]] ''et al''. (2013) observed that the lower jaw had a mid-mandibular joint.<ref name=sereno13>{{cite journal | last1 = Sereno | first1 = Paul C. | last2 = Martínez | first2 = Ricardo N. | last3 = Alcober | first3 = Oscar A. | s2cid = 86006363 | year = 2013 | title = Osteology of ''Eoraptor lunensis'' (Dinosauria, Sauropodomorpha). 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 }}</ref> It ran [[digitigrade]], and upright on its hind legs. The [[femur]] of the [[holotype]] specimen PVSJ 512 is {{convert|152|mm}}, and the [[tibia]] is {{convert|157|mm}}, suggesting that it was a fast runner. Its forelimbs are only half the length of its hindlimbs, suggesting that it was [[bipedal]]. All of its long bones have hollow shafts.<ref name=sereno13/> ''Eoraptor'' had five digits on each 'hand', the three longest of which ended in large [[claw]]s and were presumably used to handle [[prey]]. Scientists have surmised that the fourth and fifth digits were too tiny to be of any use in hunting. The [[Ilium (bone)|ilium]] is supported by three sacral vertebrae (atypical of the plesiomorphic two sacrals of basal sauropodomorphs<ref>{{Cite journal|last1=Pol|first1=Diego|last2=Garrido|first2=Alberto|last3=Cerda|first3=Ignacio A.|date=2011-01-26|title=A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum|journal=PLOS ONE|language=en|volume=6|issue=1|pages=e14572|doi=10.1371/journal.pone.0014572|issn=1932-6203|pmc=3027623|pmid=21298087|bibcode=2011PLoSO...614572P|doi-access=free}}</ref>), unlike that of the coeval ''[[Herrerasaurus]]'' which is supported by only two [[sacrum|sacrals]], a [[basal (phylogenetics)|basal]] trait.<ref>Langer, Max C. (2004). "Basal Saurischia". In [[David B. Weishampel|Weishampel, David B.]]; [[Dodson, Peter]]; and [[Halszka Osmólska|Osmólska, Halszka]] (eds.). ''The Dinosauria'' (2nd ed.). Berkeley: University of California Press. pp. 25–46. {{ISBN|0-520-24209-2}}.</ref> ''Eoraptor'' had [[Vertebral column#Dinosaurs|vertebra]]l centra that are hollow, a feature present in some of its ancestors.

[[File:Eoraptor NT small.jpg|thumb|Restoration]]
The original describers, [[Paul Sereno]] et al. (1993), supported the notion that ''Eoraptor'' was an adult specimen based on the closure of sutures in the [[vertebral column]], and the partial fusion of the [[scapulocoracoid]].<ref name=sereno93/> [[José Bonaparte|Bonaparte]] (1996) interpreted the relatively large [[Orbit (anatomy)|orbital]] opening in the skull as a juvenile trait. Ronald Tykoski agreed (2005) and suggested that certain skull features of the [[Type (biology)|type]] specimen suggested that it was young, specifically, the skull bones are not completely fused, relatively large orbits, and a short snout.<ref>Tykoski, 2005. Anatomy, ontogeny and phylogeny of coelophysoid theropods. PhD Dissertation. University of Texas at Austin. 553 pp.</ref> Later Sereno et al. (2013) considered the type specimen as a young adult approaching skeletal maturity, considering that it contained traits of both maturity and immaturity.<ref name=sereno13/>

According to Sereno ''et al''. (1993), ''Eoraptor'' can be distinguished based on the fact that its [[premaxilla]]ry and anterior [[maxilla]]ry teeth are [[Dentition#Dinosaurs|leaf-shaped]], the external [[nostril|nares]] are slightly enlarged, and the premaxilla is observed to have a slender posterolateral process.<ref name=sereno93/> Max Langer and [[Michael Benton]] (2006) noted that ''Eoraptor'' can be distinguished based on the fact that the proximal part of its [[fibula]] is extremely transversely compressed.<ref>Langer, M. C., and [[Michael Benton|Benton, M. J.]], 2006, Early Dinosaurs: a phylogenetic study: ''Journal of Systematic Palaeontology'', vol 4, n. 4, p. 309–358.</ref>

== Classification ==
In 1993 [[Paul Sereno]] and his colleagues described and named ''Eoraptor'', and determined it to be one of the earliest dinosaurs.<ref name=sereno93/><ref name="Princeton_Paul_2010">[[Gregory S. Paul|Paul, G.S.]], ''[[The Princeton Field Guide to Dinosaurs]]'' (Princeton University Press, 2010), p. 68.</ref> Its age was determined by several factors, not least because it lacked the specialized features of any of the major groups of later dinosaurs, including its lack of specialized [[predatory]] features. In 1995, Sereno posited that ''Eoraptor'' is the earliest-recorded [[Theropoda|theropod]], and is closest to "the hypothetical dinosaurian condition than any other dinosaurian subgroup."<ref>P. C. Sereno. 1995. Theropoda: early evolution and major patterns of diversification ''Journal of Vertebrate Paleontology'' 15(3, suppl.):52A-53A</ref> The precise placement of ''Eoraptor'' within Dinosauria has been unstable, with opinion often varying between a basal saurischian and a basal theropod.<ref>{{cite journal | last1 = Nesbitt | first1 = S. J. | last2 = Smith | first2 = N. D. | last3 = Irmis | first3 = R. B. | last4 = Turner | first4 = A. H. | last5 = Downs | first5 = A. | last6 = Norell | first6 = M. A. | year = 2009 | title = A complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs | journal = Science | volume = 326 | issue = 5959| pages = 1530–1533 |bibcode = 2009Sci...326.1530N |doi = 10.1126/science.1180350 | pmid = 20007898 | s2cid = 8349110 }}</ref> When it was first described by Sereno and Forster in 1993, it was regarded as a theropod, based on its "functionally tridactyl hand" and other anatomical features.<ref name=sereno93/> In 2011, a study conducted by [[Hans-Dieter Sues]], [[Sterling Nesbitt|Sterling J. Nesbitt]], David S. Berman and Amy C. Henrici featuring a description of ''[[Daemonosaurus]]'', also concluded that there is now enough fossil evidence to confidently classify ''Eoraptor'' as a theropod.<ref name="Daemonosaurus.2011.Sues&Bergman">Bergman, David S.; [[Hans-Dieter Sues|Sues, Hans-Dieter]]. (2011), [https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2011.0410 "A late-surviving basal theropod dinosaur from the latest Triassic of North America"], ''[[Proceedings of the Royal Society B]]'', published online 13-4-2011.</ref> The study noted that the "transitional suite of character states" of the recently discovered dinosaurs, ''Daemonosaurus'' and [[Tawa (dinosaur)|''Tawa'']] further support that ''Eoraptor'' is a basal theropod, and not a basal saurischian or a basal sauropodomorph.<ref name=sues11>Hans-Dieter Sues, Sterling J. Nesbitt, David S. Berman and Amy C. Henrici (2011). "A late-surviving basal theropod dinosaur from the latest Triassic of North America" ''Proceedings of the Royal Society B'' 278 (1723): 3459–3464</ref> On the other hand, several studies from 2012 onward have recovered ''Eoraptor'' as an early sauropodomorph, rather than a theropod.<ref name="sereno13"/><ref name=":0">{{Cite journal|last1=Cabreira|first1=Sergio Furtado|last2=Kellner|first2=Alexander Wilhelm Armin|last3=Dias-da-Silva|first3=Sérgio|last4=Roberto da Silva|first4=Lúcio|last5=Bronzati|first5=Mario|last6=Marsola|first6=Júlio Cesar de Almeida|last7=Müller|first7=Rodrigo Temp|last8=Bittencourt|first8=Jonathas de Souza|last9=Batista|first9=Brunna Jul’Armando|last10=Raugust|first10=Tiago|last11=Carrilho|first11=Rodrigo|date= November 2016 |title=A Unique Late Triassic Dinosauromorph Assemblage Reveals Dinosaur Ancestral Anatomy and Diet|journal=Current Biology|language=en|volume=26|issue=22|pages=3090–3095|doi=10.1016/j.cub.2016.09.040|pmid=27839975|doi-access=free|bibcode=2016CBio...26.3090C }}</ref><ref name=":1">{{Cite journal|last1=Müller|first1=Rodrigo T|last2=Langer|first2=Max C|last3=Bronzati|first3=Mario|last4=Pacheco|first4=Cristian P|last5=Cabreira|first5=Sérgio F|last6=Dias-da-Silva|first6=Sérgio|date=2018-05-15|title=Early evolution of sauropodomorphs: anatomy and phylogenetic relationships of a remarkably well-preserved dinosaur from the Upper Triassic of southern Brazil|journal=Zoological Journal of the Linnean Society|language=en|doi=10.1093/zoolinnean/zly009|issn=0024-4082}}</ref><ref>{{Cite journal|last1=Martínez|first1=Ricardo N.|last2=Apaldetti|first2=Cecilia|last3=Abelin|first3=Diego|date= November 2012 |title=Basal sauropodomorphs from the Ischigualasto Formation|journal=Journal of Vertebrate Paleontology|language=en|volume=32|issue=sup1|pages=51–69|doi=10.1080/02724634.2013.819361|bibcode=2012JVPal..32S..51M |s2cid=85720504|issn=0272-4634|url=http://doc.rero.ch/record/232879/files/PAL_E318.pdf}}</ref><ref>{{Cite journal|last=Müller|first=Rodrigo Temp|date=2019-11-12|title=Craniomandibular osteology of Macrocollum itaquii (Dinosauria: Sauropodomorpha) from the Late Triassic of southern Brazil|journal=Journal of Systematic Palaeontology|volume=18|issue=10|language=en|pages=805–841|doi=10.1080/14772019.2019.1683902|bibcode=2020JSPal..18..805M |s2cid=209575985|issn=1477-2019}}</ref><ref>{{Cite journal|last1=Pol|first1=Diego|last2=Otero|first2=Alejandro|last3=Apaldetti|first3=Cecilia|last4=Martínez|first4=Ricardo N.|date=April 2021|title=Triassic sauropodomorph dinosaurs from South America: The origin and diversification of dinosaur dominated herbivorous faunas|url=https://linkinghub.elsevier.com/retrieve/pii/S0895981120306878|journal=Journal of South American Earth Sciences|language=en|volume=107|pages=103145|doi=10.1016/j.jsames.2020.103145|bibcode=2021JSAES.10703145P|s2cid=233579282|archive-date=2021-02-14|access-date=2021-03-24|archive-url=https://web.archive.org/web/20210214005726/https://linkinghub.elsevier.com/retrieve/pii/S0895981120306878|url-status=live|url-access=subscription}}</ref><ref>{{Cite journal|last1=Müller|first1=Rodrigo Temp|last2=Garcia|first2=Maurício Silva|date=August 2020|title=A paraphyletic 'Silesauridae' as an alternative hypothesis for the initial radiation of ornithischian dinosaurs|url= |journal=Biology Letters|language=en|volume=16|issue=8|pages=20200417|doi=10.1098/rsbl.2020.0417|issn=1744-9561|pmc=7480155|pmid=32842895}}</ref><ref>{{Cite journal|last1=Ezcurra|first1=Martín D.|last2=Nesbitt|first2=Sterling J.|last3=Bronzati|first3=Mario|last4=Dalla Vecchia|first4=Fabio Marco|last5=Agnolin|first5=Federico L.|last6=Benson|first6=Roger B. 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S.|date=2020-02-01|title=Reassessment of Unaysaurus tolentinoi (Dinosauria: Sauropodomorpha) from the Late Triassic (early Norian) of Brazil, with a consideration of the evidence for monophyly within non-sauropodan sauropodomorphs|url=https://www.tandfonline.com/doi/full/10.1080/14772019.2019.1602856|journal=Journal of Systematic Palaeontology|language=en|volume=18|issue=3|pages=259–293|doi=10.1080/14772019.2019.1602856|bibcode=2020JSPal..18..259M|s2cid=182843217|issn=1477-2019|archive-date=2020-07-27|access-date=2021-03-24|archive-url=https://web.archive.org/web/20200727232643/https://www.tandfonline.com/doi/full/10.1080/14772019.2019.1602856|url-status=live|url-access=subscription}}</ref><ref>{{Cite journal|last1=Pretto|first1=Flávio A|last2=Langer|first2=Max C|last3=Schultz|first3=Cesar L|date=2019-01-18|title=A new dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Brazil provides insights on the evolution of sauropodomorph body plan|journal=Zoological Journal of the Linnean Society|volume=185|issue=2|pages=388–416|doi=10.1093/zoolinnean/zly028|issn=0024-4082|doi-access=free}}</ref><ref>{{Cite journal |last=Cau |first=Andrea |date=2018 |title=The assembly of the avian body plan: a 160-million-year-long process |url=https://doi.org/10.4435/BSPI.2018.01 |journal=Bollettino della Società Paleontologica Italiana |issue=1 |pages=1–25 |doi=10.4435/BSPI.2018.01 |doi-broken-date=2024-11-20 |issn=0375-7633}}</ref><ref>{{Cite journal|last1=Novas|first1=Fernando E.|last2=Agnolin|first2=Federico L.|last3=Ezcurra|first3=Martín D.|last4=Müller|first4=Rodrigo T.|last5=Martinelli|first5=Agustìn|last6=Langer|first6=Max|date=April 2021|title=Review of the fossil record of early dinosaurs from South America, and its phylogenetic implications|url=https://linkinghub.elsevier.com/retrieve/pii/S0895981121001887|journal=Journal of South American Earth Sciences|volume=110|language=en|pages=103341|doi=10.1016/j.jsames.2021.103341|issn=0895-9811|bibcode=2021JSAES.11003341N|archive-date=2023-11-18|access-date=2021-05-02|archive-url=https://web.archive.org/web/20231118034009/https://linkinghub.elsevier.com/retrieve/pii/S0895981121001887|url-status=live|url-access=subscription}}</ref>{{excessive citations inline|date=August 2023}} The following phylogenetic tree illustrates the relationships of ''Eoraptor'' among the major theropod groups based on various studies conducted in the 2010s.<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>

[[File:Herrerasaurusskeleton.jpg|thumb|''[[Herrerasaurus]]'' (large), ''Eoraptor'' (small), and ''[[Plateosaurus]]'' (skull), three early [[saurischia]]ns]] 
{{clade| style=font-size:90%;line-height:90%
|label1=[[Theropoda]]
|1={{clade
   |1=†[[Herrerasauridae]] [[File:Staurikosaurus pricei white background.jpg|50 px]]
   |2={{clade
      |1=†'''''Eoraptor''''' [[File:Royal Ontario Museum Eoraptor white background.JPG|50 px]]
      |2={{clade
      |1=†''[[Eodromaeus]]'' [[File:Eodromaeus.jpg|50 px]]
      |2={{clade
         |1=†''[[Daemonosaurus]]''
         |2={{clade
            |1=†''[[Tawa (dinosaur)|Tawa]]''
            |label2=[[Neotheropoda]]
            |2={{clade
               |1=†[[Coelophysoidea]]&nbsp; [[File:Coelophysis (1) white background.jpg|50 px]]
               |2={{clade
                  |1=†[[Dilophosauridae]]
|label2=[[Averostra]]
      |2={{clade
      |1=†[[Ceratosauria]] [[File:Dinossauromcnpucminas white background.jpg|50px]]
      |2=[[Tetanurae]] [[File:Allosaurus AMNH White Background.jpg|50px]]
                           }}
                        }}
                     }}
                  }}
               }}
            }}
         }}
                           }}
                        }}

[[File:Eoraptor Japan.jpg|thumb|Replica skeleton in Japan]]  
[[Philip J. Currie|Philip Currie]] (1997) found ''Eoraptor'' anatomically closer to what would be considered the ancestral [[Polymorphism (biology)|morphotype]] of both [[saurischia]]n and [[ornithischia]]n dinosaurs.<ref>[[Philip J. Currie|Currie, P.J.]] (1997). Theropoda. In ''Encyclopedia of Dinosaurs'' (P.J. Currie and K. Padian, eds.) pp 731–736. Academic Press, San Diego, California.</ref> In 2011, Martinez ''et al.'' (the team that described ''[[Eodromaeus]])'' found ''Eoraptor'' to be a basal sauropodomorph, with characteristic features from the group.<ref>{{cite journal |last1=Martinez |first1=Ricardo N. |last2=Sereno |first2=Paul C. |author-link2=Paul Sereno |last3=Alcober |first3=Oscar A. |last4=Colombi |first4=Carina E. |last5=Renne |first5=Paul R. |last6=Montañez |first6=Isabel P. |last7=Currie |first7=Brian S. |year=2011 |title=A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea |journal=Science |volume=331 |issue=6014 |pages=206–10 |bibcode=2011Sci...331..206M |doi=10.1126/science.1198467 |pmid=21233386 |s2cid=33506648 |hdl-access=free |hdl=11336/69202}}</ref><ref name="NNews_2011">Kaplan, M. [http://www.nature.com/news/2011/110113/full/news.2011.17.html "Move over ''Eoraptor''"] {{Webarchive|url=https://web.archive.org/web/20120601131827/http://www.nature.com/news |date=2012-06-01 }}, ''http://www.nature.com/news'', 13-1-2011.</ref> Michael Benton expressed his hesitation to this, and claimed that it is "quite a shift" to remove ''Eoraptor'' from Theropoda and then place it in Sauropodomorpha.<ref name="NNews_2011"/> A subsequent study by Apaldetti, Martinez, Alcober, and Pol published in 2011 found ''Eoraptor'' to be a saurischian close to sauropodomorphs and theropods, though was unable to resolve which of the two branches, if either, it fell within.<ref name=Apaldetti2011>{{cite journal | last1 = Apaldetti | first1 = C | last2 = Martinez | first2 = RN | last3 = Alcober | first3 = OA | last4 = Pol | first4 = D  | 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| page = e26964 | doi = 10.1371/journal.pone.0107672 | pmid = 25259845 | pmc = 4178034 | doi-access = free }}</ref> Sereno ''et al''. (2013) redescribed the holotype skeleton and concluded that ''Eoraptor'' was not a theropod but a basal sauropodomorph, consistent with the earlier observation made by Martinez ''et al''. (2011).<ref name=sereno13/>

A large phylogenetic analysis of early dinosaurs by Matthew Baron, [[David B. Norman|David Norman]] and Paul Barrett (2017) found ''Eoraptor'' to be the earliest diverging member of [[Theropoda]], within the larger clade [[Ornithoscelida]].<ref name="Ornithoscelida">{{cite journal | last1 = Baron | first1 = M.G. | last2 = Norman | first2 = D.B. | last3 = Barrett | first3 = P.M. | s2cid = 205254710 | 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 }}</ref> A phylogenetic analysis published with the description of new ''[[Buriolestes]]'' remains in 2018, based on Langer ''et al.'' (2017)<ref>{{Cite journal |last1=Langer |first1=Max C. |last2=Ezcurra |first2=Martín D. |last3=Rauhut |first3=Oliver W. M. |last4=Benton |first4=Michael J. |author-link4=Michael Benton |last5=Knoll |first5=Fabien |last6=McPhee |first6=Blair W. |last7=Novas |first7=Fernando E. |last8=Pol |first8=Diego |last9=Brusatte |first9=Stephen L. |author-link9=Stephen L. Brusatte |year=2017 |title=Untangling the dinosaur family tree |url=https://research-information.bristol.ac.uk/en/publications/untangling-the-dinosaur-family-tree(d088dae2-c7fa-4d41-9fa2-aeebbfcd2fa3).html |journal=Nature |volume=551 |issue=7678 |pages=E1–E3 |bibcode=2017Natur.551E...1L |doi=10.1038/nature24011 |pmid=29094688 |s2cid=205260354 |hdl=1983/d088dae2-c7fa-4d41-9fa2-aeebbfcd2fa3|hdl-access=free }}</ref> placed ''Eoraptor'' in a clade of early sauropodomorphs, alongside ''Buriolestes'', ''[[Panphagia]]'', ''[[Pampadromaeus]]'', and ''[[Saturnalia tupiniquim|Saturnalia]]''.<ref name="Muller2018">{{Cite journal|last1=Müller|first1=Rodrigo T.|last2=Langer|first2=Max C.|last3=Bronzati|first3=Mario|last4=Pacheco|first4=Cristian P.|last5=Cabreira|first5=Sérgio F.|last6=Dias-da-Silva|first6=Sérgio|s2cid=90215853|date=15 May 2018|title=Early evolution of sauropodomorphs: anatomy and phylogenetic relationships of a remarkably well-preserved dinosaur from the Upper Triassic of southern Brazil|journal=Zoological Journal of the Linnean Society|language=en|volume=184|issue=4|pages=1187–1248|doi=10.1093/zoolinnean/zly009}}</ref>

== Paleobiology ==
''Eoraptor'' is thought to have been an omnivore,<ref name="sereno13"/> although its [[dentition]] is quite similar to that of ''[[Buriolestes]]'', which is considered carnivorous.<ref name=":0"/><ref name=":1"/> It was a swift sprinter and, upon catching its prey, it would use claws and teeth to tear the prey apart. Unlike later [[carnivorous]] dinosaurs, it lacked a sliding joint at the articulation of the lower jaw, with which to hold large prey. Furthermore, only some of its teeth were curved and saw-edged, unlike those in the mouths of later theropods. The heterodont dentition of ''Eoraptor'' consists of both serrated, recurved teeth in the upper jaw, like the teeth of theropods, and leaf-shaped teeth in the lower jaw, like the teeth of basal sauropodomorphs.<ref name="sereno93">{{cite journal |last1=Sereno |first1=P.C. |author-link=Paul Sereno |last2=Forster |first2=C.A. |author-link2=Catherine Forster |last3=Rogers |first3=R.R. |author-link3=Raymond R. Rogers |last4=Moneta |first4=A.M. |year=1993 |title=Primitive dinosaur skeleton from Argentina and the early evolution of the Dinosauria |journal=Nature |volume=361 |issue=6407 |pages=64–66 |bibcode=1993Natur.361...64S |doi=10.1038/361064a0 |s2cid=4270484}}</ref> ''Eoraptor'' had 4 teeth in the [[premaxilla]] and 18 teeth in the [[maxilla]], a [[dental formula]] not dissimilar to that of ''[[Herrerasaurus]]''.

== Paleoecology ==
[[File:Eoraptor lunensis.jpg|thumb|Backbone and upper limbs outcropping from the soil, [[Valle de la Luna (Argentina)|Valle de la Luna]], [[Argentina]]]]
During the Late Triassic period, the Ischigualasto Formation was a volcanically active [[floodplain]] covered by forests, with a warm and humid climate,<ref name="TuckerBenton1982">{{cite journal |last1=Tucker |first1=Maurice E. |author-link=Maurice Tucker |last2=Benton |first2=Michael J. |author-link2=Michael Benton |year=1982 |title=Triassic environments, climates, and reptile evolution |url=http://palaeo.gly.bris.ac.uk/benton/reprints/1982triassic.pdf |url-status=dead |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=40 |issue=4 |pages=361–379 |bibcode=1982PPP....40..361T |doi=10.1016/0031-0182(82)90034-7 |archive-url=https://web.archive.org/web/20090126214339/http://palaeo.gly.bris.ac.uk/benton/reprints/1982triassic.pdf |archive-date=2009-01-26 |access-date=2009-07-23}}</ref> but subject to seasonal variations including strong rainfall.<ref name="Columbi2008">{{cite conference| first = Carina E.| last = Columbi| title = Stable isotope analysis of fossil plants from the Upper Triassic Ischigualasto Formation in the northwest of Argentina| publisher = The Geological Society of America| date = 2008-10-05| location = Houston, TX| url = http://gsa.confex.com/gsa/2008AM/finalprogram/abstract_151184.htm| access-date = 2009-07-23| archive-url = https://web.archive.org/web/20120111145256/http://gsa.confex.com/gsa/2008AM/finalprogram/abstract_151184.htm| archive-date = 2012-01-11| url-status = dead}}</ref> [[Vegetation]] consisted of [[fern]]s, [[Equisetum|horsetails]], and giant [[Pinophyta|conifers]], which formed [[Highland (geography)|highland]] forests along the banks of rivers.<ref name ="Sereno1992">{{cite journal |last1=Sereno |first1=P.C. |last2=Novas |first2=F.E. |title=The complete skull and skeleton of an early dinosaur |journal=Science |volume=258 |year=1992 |pages=1137–1140 |doi=10.1126/science.258.5085.1137 |pmid=17789086 |issue=5085|bibcode = 1992Sci...258.1137S |s2cid=1640394 }}</ref> ''[[Herrerasaurus]]'' remains appear to have been the most common among the carnivores of the Ischigualasto Formation.<ref>{{cite journal |last1=Rogers |first1=R. R. |author-link=Raymond R. Rogers |last2=Swisher |first2=III |last3=Sereno |first3=P.C. |author-link3=Paul Sereno |last4=Monetta |first4=A.M. |last5=Forster |first5=C.A. |author-link5=Catherine Forster |last6=Martinez |first6=R.N. |year=1993 |title=The Ischigualasto tetrapod assemblage (Late Triassic, Argentina) and 40Ar/39Ar dating of dinosaur origins |journal=Science |volume=260 |issue=5109 |pages=794–797 |bibcode=1993Sci...260..794R |doi=10.1126/science.260.5109.794 |pmid=17746113 |s2cid=35644127}}</ref> Sereno (1993) noted that ''Eoraptor'' was found in "close association" with [[therapsid]]s, [[rauisuchia]]ns, [[archosaur]]s, ''[[Saurosuchus]]'' and the dinosaurs ''Herrerasaurus'' and ''[[Pisanosaurus]]'', all of whom lived in its paleoenvironment. [[Herbivore]]s were represented by [[rhynchosaur]]s such as ''[[Hyperodapedon]]''; [[aetosaur]]s; [[cynodont]]s like ''[[Chiniquodon]]'', [[Kannemeyeria|kannemeyeriid]] [[dicynodont]]s such as ''[[Ischigualastia]]''; and [[traversodontidae|traversodontids]] such as ''[[Exaeretodon]]''. These non-dinosaurian herbivores were much more abundant than early dinosaurs.<ref>{{cite journal |last=Bonaparte |first=J.F. |author-link=José Bonaparte |year=1970 |title=Annotated list of the South American Triassic tetrapods |journal=Gondwana Symposium Proceedings and Papers |volume=2 |pages=665–682}}</ref> Dinosaur fossils, including those of ''Eoraptor'' only represent approximately 6% of the total sample that has been recovered from the Ischigualasto Formation (Rogers ''et al''., 1993), which suggests that dinosaurs were less numerous than other [[tetrapod]]s.<ref>{{cite journal | last1 = Rogers | first1 = R. R. | last2 = Swisher | first2 = C. C. III | last3 = Sereno | first3 = P. C. | last4 = Monetta | first4 = A. M. | last5 = Forster | first5 = C. A. | last6 = Martinez | first6 = R. N. | year = 1993 | title = The Ischigualasto Tetrapod Assemblage (Late Triassic, Argentina) and 40Ar/39Ar Dating of Dinosaur Origins | journal = Science | volume = 260 | issue = 5109| pages = 794–797 | doi=10.1126/science.260.5109.794 | pmid = 17746113| bibcode = 1993Sci...260..794R | s2cid = 35644127 }}</ref>

== References ==
{{Reflist|2}}

== External links ==
* {{Commons category-inline|Eoraptor|''Eoraptor''}}
* {{Wikispecies-inline|Eoraptor|''Eoraptor''}}
* [http://www.paulsereno.org Paul Sereno's paleontology website]
* [https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=57453 Paleobiology Database entry]
* [http://digimorph.org/specimens/Eoraptor_lunensis/ ''Eoraptor lunensis''] at [[DigiMorph]]

{{Theropoda|N.|state=collapsed}}
{{Sauropodomorpha|S.|state=collapsed}}
{{Taxonbar|from=Q130988}}
{{Portal bar|Argentina|Dinosaurs|Paleontology}}

[[Category:Dinosaur genera]]
[[Category:Sauropodomorpha]]
[[Category:Carnian dinosaurs]]
[[Category:Ischigualasto Formation]]
[[Category:Fossil taxa described in 1993]]
[[Category:Taxa named by Paul Sereno]]
[[Category:Dinosaurs of Argentina]]