Editing Staurikosaurus

{{Short description|Extinct genus of dinosaurs}}
{{speciesbox
| fossil_range = [[Late Triassic]], {{fossil range|233.23|228}}
| image = Staurikosaurus pricei.jpg
| image_upright = 1.1
| image_caption = Reconstructed skeleton
| genus = Staurikosaurus
| parent_authority = [[Edwin Harris Colbert|Colbert]], [[1970 in paleontology|1970]]
| species = pricei
| authority = Colbert, 1970
| synonyms = * ''Teyuwasu barberenai'' <small>Kischlat, 1999</small>
}}

'''''Staurikosaurus''''' (Pronounced [[Help:IPA/English|/ˌstɔɹ̠ikoʊˈsɔɹ̠ʌs/]], ''[[Help:Pronunciation_respelling_key|STOR-ree-koh-SOR-ruhs]]''; "[[Crux|Southern Cross]] lizard") is a [[genus]] of [[Herrerasauridae|herrerasaurid]]<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 | doi = 10.1126/science.1180350 | pmid = 20007898 | bibcode = 2009Sci...326.1530N | s2cid = 8349110 }}</ref> [[dinosaur]] from the [[Late Triassic]] of [[Brazil]], found in the [[Santa Maria Formation]].

== Description ==
[[File:Staurikosaurus size.jpg|alt=|left|thumb|Size comparison between ''Staurikosaurus'' and a human]]
Colbert (1970) described ''Staurikosaurus'' as a small and agile, [[Bipedalism|bipedal]] predator.<ref name="colbert1970">Colbert, E. H. (1970). A Saurischian dinosaur from the Triassic of Brazil. AM. MUS. NOVITATES 2405; 1-39</ref> ''Staurikosaurus'' lived during the late-[[Carnian]] and early-[[Norian]] stage, of the [[Triassic|Late Triassic]], approximately 225 million years ago—which makes it one of the earliest dinosaurs known. Its length is measured at {{convert|2.2|-|2.25|m}} long,<ref name="caudalposition">Grillo, O.N. and Azevedo, S.A.K. (2011). "Recovering missing data: estimating position and size of caudal vertebrae in ''Staurikosaurus pricei'' Colbert, 1970." ''Annals of the Brazilian Academy of Sciences'',</ref> but [[Gregory S. Paul]] presented a lower length estimate of {{convert|2.1|m}} and a body mass estimate of {{convert|12|kg}}.<ref>{{Cite book|last=Paul|first=Gregory S.|url=http://worldcat.org/oclc/985402380|title=The Princeton Field Guide to Dinosaurs|year=2016|publisher=Princeton University Press|isbn=978-1-78684-190-2|oclc=985402380|pages=81}}</ref> ''Staurikosaurus'' was small in comparison to later theropods like ''[[Megalosaurus]]''. The type specimen has long but relatively slender limb bones.

There exists a very incomplete fossil record of ''Staurikosaurus'', consisting of most of the spine, the legs and the large lower jaw. However, dating from such an early period in the dinosaurs' history and being otherwise so primitive, most of ''Staurikosaurus''' other features as being primitive also can be reconstructed. For example, ''Staurikosaurus'' is usually depicted with five toes and five fingers<ref name="ageofdinosaursstaurikosaurus"/>—very simple features of an unspecialized dinosaur. However, since the skeletal structure of the legs is known, it can be seen that ''Staurikosaurus'' was a quick runner for its size. It also had just two [[vertebra]]e joining the [[pelvis]] to the [[vertebral column|spine]], a distinctly primitive condition.

The available teeth for ''Staurikosaurus'' bear a morphology that strongly suggests a carnivorous diet. The teeth are all serrated, laterally compressed, and caudally curved (i.e. the top of each tooth is curved back toward the throat).<ref name=":1">Bittencourt, J.S. & Kellner, A.W.A., 2009. [https://www.biotaxa.org/Zootaxa/article/view/zootaxa.2079.1.1 The anatomy and phylogenetic position of the Triassic dinosaur Staurikosaurus pricei Colbert, 1970]. Zootaxa 2079, 1–56.</ref> This dentition suggests that ''Staurikosaurus'' could catch and hold prey, as well as slice and tear flesh to aid in mechanical digestion.<ref name="langer04">Langer, M. C., 2004, Basal Saurischia, Chapter Two: In: The Dinosauria, Second Edition, edited by Weishampel, D.B., Dodson, P., and Osmolska, H., California University Press, p. 25-46.</ref>

The tail of ''Staurikosaurus'' was relatively long (with more than 40 vertebrae) compared to the rest of its body and was held straight and off the ground as it ran. The rear part of ''Staurikosaurus''{{'}}s tail is stiffened by features of the tail vertebrae. Ostrom (1969a) considered this adaptation to serve as a dynamic stabilizer facilitating the animal's leaping and running.<ref>J. H. Ostrom. 1969. Osteology of Deinonychus antirrhopus, an unusual theropod from the Lower Cretaceous of Montana. Peabody Museum Bulletin 30:1-165</ref>
[[File:Staurikosaurus-mingau-colour.png|left|thumb|Paleoart of ''Staurikosaurus.'']]
A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism or group. According to Sues (1990), ''Staurikosaurus'' can be distinguished based on the following 14 features: (i) a [[mandible]] almost as long as the [[femur]], suggesting a proportionately large head; (ii) a fairly deep but thin [[dentary]] with 13 to 14 teeth and with a well-developed retroarticular process; (iii) a vertebral column with 9 to 10 cervical, 15 dorsal, 2 [[Sacrum|sacral]], and more than 40 caudal vertebrae. ''Staurikosaurus'' is considered to be more primitive than any other dinosaur because only two sacral vertebrae are present; (iv) an elongated 3rd, 4th, and 5th cervical vertebrae, which represents a primitive condition; (v) cranial cervical vertebrae that lack epipophyses; (vi) the absence of accessory intervertebral articulations; (vii) a slender scapular blade that is not expanded proximally; (viii) a large and plate-like [[coracoid]]; (ix) a [[humerus]] featuring a prominent deltopectoral crest (represents a primitive condition) as well having distinctly expanded articular ends; (x) an [[Ilium (bone)|ilium]] with an extensively developed medial wall of a semiperforate [[Acetabulum#Perforate Acetabulum|acetabulum]] (like ''Herrerasaurus'', but unlike any other dinosaur); (xi) a long [[Pubis (bone)|pubis]], two-thirds the length of the [[femur]]; (xii) hollow limb bones that feature fairly thick walls; (xiii) a robust femur with an S-shaped shaft: and (xiv) a [[tibia]] and [[fibula]] slightly longer than the femur.<ref>Sues, 1990. ''Staurikosaurus'' and Herrerasauridae. in Weishampel, et al. (eds.). The Dinosauria. University of California Press, Berkeley, Los Angeles, Oxford. 143-147.</ref> Novas (1993) added that ''Staurikosaurus'' is distinguished from other dinosaurs based on the presence of a distal bevel on anterior margin of its pubis.<ref>Novas, 1993. New information on the systematics and postcranial skeleton of ''Herrerasaurus ischigualastensis'' (Theropoda: Herrerasauridae) from the Ischigualasto Formation (Upper Triassic) of Argentina. Journal of Vertebrate Paleontology 13 p. 400-423.</ref> Langer and Benton (2006) noted that ''Staurikosaurus'' can be distinguished based on the anterior trochanter being reduced to a scar.<ref>{{cite journal | last1 = Langer | last2 = Benton | year = 2006 | title = Early dinosaurs: A phylogenetic study | journal = Journal of Systematic Palaeontology | volume = 4 | issue = 4| pages = 309–358 | doi = 10.1017/s1477201906001970 | bibcode = 2006JSPal...4..309L | s2cid = 55723635 }}</ref> Bittencourt and Kellner (2009) also noted that the proximal fibula has a medial sulcus, which is unique to ''Staurikosaurus pricei.''<ref name=":1" />

== Discovery and occurrence ==
[[File:Staurikosaurus reconstruction.jpg|alt=|thumb|Reconstructed skeleton showing known remains in white, and unknown in gray]]
''Staurikosaurus'' is named after the "[[Crux|Southern Cross]]" the star constellation visible from the Southern Hemisphere (from the Greek “Stauros” meaning cross and "saurus" meaning lizard), thus "Cross Lizard".<ref name=Paleofile>{{cite web|url=http://www.paleofile.com/Dinosaurs/Theropods/Staurikosaurus.asp|title=Staurikosaurus COLBERT, 1970|website=Paleofile|archive-url=https://web.archive.org/web/20230801185042/http://www.paleofile.com/Dinosaurs/Theropods/Staurikosaurus.asp|archive-date=2023-08-01|url-status=dead}}</ref><ref>{{cite web|url=https://www.nhm.ac.uk/discover/dino-directory/staurikosaurus.html|title=Staurikosaurus|publisher=[[Natural History Museum, London]]|archive-url=https://web.archive.org/web/20221127123702/https://www.nhm.ac.uk/discover/dino-directory/staurikosaurus.html|archive-date=2022-11-27|url-status=live}}</ref> The species name ''pricei'' is in the honor of paleontologist [[Llewellyn Ivor Price]].<ref name=Paleofile/>

The first known specimen of ''Staurikosaurus'' (MCZ 1669) was recovered from the [[Paleontological Site Jazigo Cinco]] of the [[Santa Maria Formation]],<ref name="ageofdinosaursstaurikosaurus">"Staurikosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. ''The Age of Dinosaurs''. Publications International, LTD. p. 45. {{ISBN|0-7853-0443-6}}.</ref> [[Rio Grande do Sul]], southern [[Brazil]]. ''Staurikosaurus'' was found in mid-Carnian sediments. The genus name refers to the [[star]] [[constellation]] "The [[Crux|Southern Cross]]", pictured in the [[coat of arms of Brazil]] and only visible in the [[Southern Hemisphere]]—when ''Staurikosaurus'' was described in 1970,<ref name="colbert1970" /> it was unusual to find dinosaurs in the Southern Hemisphere. The [[specific name (zoology)|specific name]] honors the Brazilian [[Paleontology|paleontologist]] [[Llewellyn Ivor Price]], who discovered it in 1936. It was described by [[Edwin Harris Colbert]], working at the [[American Museum of Natural History]]. The rarity of ''Staurikosaurus'' remains may be a result of it being uncommon while alive, or because it lived in an environment like a forest, where fossils rarely form.<ref name="ageofdinosaursstaurikosaurus" /> Nonetheless, Garcia et al. (2019) referred the [[holotype]] of ''Teyuwasu barberenai'' as a second specimen of ''Staurikosaurus pricei'' (see Classification).<ref name=":0" />

== Classification ==
Later research by Sues et al. (2011) supports that ''Staurikosaurus'' and the related genus ''[[Herrerasaurus]]'' are theropods and evolved after the sauropod line had split from the Theropoda.<ref name=sues11/> Mortimer points out that Benedetto (1973) and Galton (1985) were the first to recognize that ''Staurikosaurus'' and ''Herrerasaurus ''were more closely related to each other than to sauropodomorphs or avepods, placing them both in the Herrerasauridae and Herrerasauria.<ref>{{cite web|url=http://archosaur.us/theropoddatabase/Non-theropods.htm#Staurikosauruspricei |last=Mortimer|first=Mickey|year=2012|title=Non-theropods}}</ref><ref>{{cite journal | last1 = Benedetto | year = 1973 | title = Herrerasauridae, nueva familia de saurisquios triasicos | journal = Ameghiniana | volume = 10 | issue = 1| pages = 89–102 }}</ref><ref>Galton, 1985. "The poposaurid thecodontian ''Teratosaurus suevicus'' v. Meyer, plus referred specimens mostly based on prosauropod dinosaurs, from the Middle Stubensandstein (Upper Triassic) of Nordwurttemberg". ''Stuttgart Beitrage zur Naturkunde ''(B). 116, 1-29.</ref> ''Staurikosaurus'' differs from ''Herrerasaurus'' because of its considerably smaller size (femur length of {{convert|23|cm}} vs. {{convert|47|cm}}). Sereno et al. (1993) concluded that ''Staurikosaurus'' was not a theropod and considered it a basal saurischian outside Theropoda and Sauropodomorpha.<ref>{{cite journal | last1 = Sereno | first1 = P. C. | year = 1993 | title = The pectoral girdle and forelimb of the basal Theropod ''Herrerasaurus ischigualastensis'' | journal = Journal of Vertebrate Paleontology | volume = 13 | issue = 4| pages = 425–450 | doi = 10.1080/02724634.1994.10011524 }}</ref>''Staurikosaurus'' was originally incorrectly assigned by Colbert to Palaeosauriscidae, a defunct family based largely on ''[[Efraasia]]'', a prosauropod dinosaur. All major phylogenetic analyses since 1994 have assigned ''Staurikosaurus'' to the clade [[Herrerasauridae]], which is the current scientific consensus on classification of this genus. Bittencourt and Kellner (2009) stated that the phylogenetic position of ''Staurikosaurus'' is constrained by its close relationship with ''Herrerasaurus ischigualastensis'', which is more complete and well known.<ref name=":1" /> Below is a [[cladogram]] based on the phylogenetic analysis conducted by Sues et al. in 2011, showing the relationships of ''Staurikosaurus'':<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>

[[File:Staurikosaurus.jpg|thumb|upright|Restored skeleton]]
[[File:Staurikosaurus new NT.jpg|thumb|right|Restoration of ''Staurikosaurus pricei'']]
{{clade| style=font-size:90%;line-height:75%
|label1=[[Theropoda]]
|1={{clade
   |label1=[[Herrerasauridae]]
   |1={{clade
      |1='''''Staurikosaurus'''''
      |2={{clade
         |1=''[[Herrerasaurus]]''
         |2=''[[Chindesaurus]]'' }} }}
   |2={{clade
      |1=''[[Eoraptor]]''
      |2={{clade
         |1=''[[Daemonosaurus]]''
         |2={{clade
            |1=''[[Tawa (dinosaur)|Tawa]]''
            |label2=[[Neotheropoda]]
            |2={{clade
               |label1=[[Coelophysidae]]
               |1={{clade
                  |1=''[[Megapnosaurus]]''
                  |2=''[[Coelophysis]]''}}
               |2={{clade
                  |1=''[[Liliensternus]]''
                  |2={{clade
                     |1=''[[Zupaysaurus]]''
                     |2={{clade
                        |1=''[[Cryolophosaurus]]''
                        |2={{clade
                           |1=''[[Dilophosaurus]]''
                           |2=[[Jurassic]] theropods }} }} }} }} }} }} }} }} }} }}

=== Related genera ===
''Staurikosaurus'' was placed in the clade [[Herrerasauridae]] by Benedetto in 1973. Herrerasauridae also includes ''[[Herrerasaurus]] ischigualastensis'', both small predatory animals that were either dinosaurs or precursors to dinosaurs.<ref name="novas1997">Novas, F.E. 1997. Herrerasauridae. In P.J. Currie and K. Padian (eds.). Encyclopedia of Dinosaurs. Academic Press.</ref> These three dinosaurs lived during the Carnian stage of the Triassic period. Most phylogenetic analyses excluded ''[[Eoraptor]]'' from the Herrerasauridae.<ref>{{cite journal | last1 = Novas | first1 = Fernando E. | last2 = Ezcurra | first2 = Martin D. | last3 = Chatterjee | first3 = Sankar | last4 = Kutty | first4 = T. S. | 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> Phylogenetic analysis by Sues, Nesbitt, Berman and Henrici, in 2011, exclude ''[[Eoraptor]]'', and include ''[[Chindesaurus]]'' along with ''[[Herrerasaurus]]'' as more derived than ''Staurikosaurus''.<ref>{{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> ''[[Sanjuansaurus]]'' was assigned to Herrerasauridae by Alcober and Martínez (2010).<ref>{{cite journal | last1 = Alcober | first1 = O. A. | last2 = Martínez | first2 = R. 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 | doi-access = free | bibcode = 2010ZooK...63...55A }}</ref> Sues (1990) assigned [[Ischisaurus]] to Herrerasauridae.<ref>H.-D. Sues. 1990. ''Staurikosaurus'' and Herrerasauridae. In D. B. Weishampel, H. Osmólska, and P. Dodson (eds.), The Dinosauria. University of California Press, Berkeley 143-147</ref> Other proposed members of the [[clade]] have included ''[[Sanjuansaurus]]''<ref name=OARM2010>{{cite journal |last=Alcober |first=Oscar A. |author2=Martinez, Ricardo N. |year=2010 |title=A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina |journal=ZooKeys |pages=55–81 |doi=10.3897/zookeys.63.550 |pmid=21594020 |pmc=3088398 |issue=63|doi-access=free |bibcode=2010ZooK...63...55A }}</ref> from the same [[Ischigualasto|Ischigualasto Formation]] of Argentina as ''Herrerasaurus'', and possibly ''[[Caseosaurus]]'' from the [[Dockum Group|Dockum Formation]] of Texas,<ref>{{cite journal|last=Hunt|first=A.P.|author2=Lucas, S.G. |author3=Heckert, A.B. |author4=Sullivan, R.M. |author5= Lockley, M.G. |year=1998|title=Late Triassic Dinosaurs from the Western United States| journal=Geobios|volume=31|issue=4|pages=511–531|doi=10.1016/S0016-6995(98)80123-X|bibcode=1998Geobi..31..511H }}</ref> although the relationships of these animals are not fully understood, and not all paleontologists agree. Alcober and Martinez (2010) concluded that ''Staurikosaurus'' and ''Sanjuansaurus'' are closely related based on similarities in their [[Pubis (bone)|pubis]] and [[tibia]].<ref>{{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 | doi-access = free | bibcode = 2010ZooK...63...55A }}</ref>

=== Synonyms ===
[[File:Teyuwasu barberenai.png|200px|thumb|left|Femur and tibia holotype of ''Teyuwasu barberenai'' (BSPG AS XXV 53).]]
The controversial [[Dinosauriformes|dinosauriform]] ''"Teyuwasu barberenai"'' was recently considered a [[Synonym (taxonomy)|synonym]] of ''Staurikosaurus pricei''.<ref name=":0">{{Cite journal|last1=Garcia|first1=Maurício S.|last2=Müller|first2=Rodrigo T.|last3=Dias-Da-Silva|first3=Sérgio|date=2019-07-04|title=On the taxonomic status of Teyuwasu barberenai Kischlat, 1999 (Archosauria: Dinosauriformes), a challenging taxon from the Upper Triassic of southern Brazil|url=https://biotaxa.org/Zootaxa/article/view/zootaxa.4629.1.12|journal=Zootaxa|volume=4629|issue=1|pages=146–150|doi=10.11646/zootaxa.4629.1.12|issn=1175-5334|pmid=31712541|s2cid=198274900 |url-access=subscription}}</ref> Both taxa are known from single incomplete and somewhat poorly preserved specimens, therefore the former holotype specimen of "''Teyuwasu"'' would be the second specimen ascribed to ''Staurikosaurus'' within almost 50 years of its naming.<ref name="colbert1970" /><ref name=":0" /> The synonymy was based on a combination of five osteological features that are only present in both specimens among Triassic early dinosauriforms: (i) femur without a trochanteric shelf; (ii) symmetric fourth trochanter of the femur; (iii) crista tibiofibularis poorly separated from the lateral condyle at the distal end of the femur; (iv) posterolateral flange of the distal end of the tibia does not exceeds the lateral margin of the bone; (v) and rounded distal end of the tibia.

The synonymy is commented in two subsequent papers, which cast doubt in the association of "Teyuwasu" with ''Staurikosaurus''. In the first paper, the authors only mention that the holotype of "''Teyuwasu"'' is not well preserved, and thus cannot be attributed to ''Staurikosaurus''.<ref>{{Cite journal|last1=Desojo|first1=Julia|last2=von Baczko|first2=María|last3=Rauhut|first3=Oliver|date=2020|title=Anatomy, taxonomy and phylogenetic relationships of Prestosuchus chiniquensis (Archosauria: Pseudosuchia) from the original collection of von Huene, Middle-Late Triassic of southern Brazil|url=https://palaeo-electronica.org/content/2020/2917-type-materials-of-prestosuchus|journal=Palaeontologia Electronica|volume=23|issue=1|pages=1–55|doi=10.26879/1026|doi-access=free|hdl=11336/127498|hdl-access=free}}</ref> In the second, the authors argue that several of the five character states cited to unite the taxa are present in immature specimens of other dinosauriforms.<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|bibcode=2021JSAES.11003341N |url-access=subscription}}</ref> However, the combination (that is, the simultaneous presence) of the five characters listed by Garcia et al.<ref name=":0" /> is not present in any of the aforementioned dinosauriforms, and therefore remains unique between "''Teyuwasu''" and ''Staurikosaurus''.{{Citation needed|date=October 2023}}

Therefore, further investigations are needed in order to whether confirm or not the synonymy between "''Teyuwasu barberenai''" and ''Staurikosaurus pricei''.

== Paleobiology ==
[[File:Staurikosaurus DB.jpg|thumb|''Staurikosaurus'' with a [[rhynchosaur]]]]

=== Feeding ===
''Staurikosaurus'' was a small but active bipedal predator, that preyed on small and medium-sized terrestrial vertebrates such as [[cynodont]]s, [[rhynchosaur]]s, and herbivorous [[synapsid]]s. The mandible of ''Staurikosaurus'' suggests that a sliding joint in the jaw allowed it to move backwards and forwards, as well as up and down. However, some authors questioned the presence of an intramandibular joint in ''Staurikosaurus'', due to the poor preservation of the holotype.<ref name=":1" /> Smaller prey could be worked backwards towards ''Staurikosaurus''{{'}}s throat, aided along by its small, backwards-curving teeth.<ref name="langer04"/> This feature was common in theropods of its time, but would disappear in later theropods.

== Paleoecology ==
[[File:Estauricossauro rincossauro.JPG|thumb|Statues of ''Staurikosaurus'' and a [[rhynchosaur]] at [[Canela, Rio Grande do Sul|Canela]], Brazil]]
During the Late Triassic dinosaurs played only a minor role in terrestrial life; a fact that would change by the Early Jurassic. ''Staurikosaurus'' coexisted with large [[rauisuchia]]n [[archosaur]]s like ''[[Rauisuchus]]'', which were the top carnivores in their ecosystem<ref>J.F. Bonaparte, 1982, "Faunal Replacement in the Triassic of South America", Journal of Vertebrate Paleontology 2 (3): 362-371, December 1982.</ref> ''Staurikosaurus''{{'}}s paleocommunity included medium- to large-sized herbivorous [[rhynchosaur]]s and [[dicynodont]]s. Medium-sized omnivorous [[aetosaur]]s and [[cynodont]]s were also present. Dinosaurs were represented by the Herrerasaurids, which include ''Staurikosaurus'', and the basal [[sauropodomorph]] ''[[Saturnalia (dinosaur)|Saturnalia]]''. The contemporaneous occurrence of basal theropods ''Staurikosaurus'', ''Herrerasaurus'', and ''Eoraptor'' with the ornithischian ''Pisanosaurus'' suggests that the main carnivorous and herbivorous lineages were established during the middle part of the Carnian stage.<ref name="novas1997"/> A U-Pb ([[uranium]] decay) dating found that the Santa Maria Formation dated around 233.23 million years ago, putting it 1.5 million years older than the [[Ischigualasto Provincial Park|Ischigualasto Formation]], and making the two formations approximately equal as the earliest dinosaur localities.<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|doi=10.1016/j.gr.2018.01.005|pages=133–140|bibcode=2018GondR..57..133L }}</ref>

== See also ==

* [[Herrerasaurus]] 
* [[Panphagia]] 
* [[Eoraptor]]
* [[List of dinosaur genera]]

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

== External links ==
{{Portal|Brazil|Dinosaurs|Paleontology}}
* {{Commons category-inline|Staurikosaurus|''Staurikosaurus''}}
* {{Wikispecies-inline|Staurikosaurus|''Staurikosaurus''}}
* [https://doodles.google/doodle/celebrating-the-staurikosaurus Doodle celebrates the Staurikosaurus, one of the earliest dinosaurs ever discovered | Oct 19, 2024]
* [http://www.royalsul.com.br/paleo/galeria.asp Dinosaurs of Rio Grande do Sul]

{{Avemetatarsalia}}
{{Taxonbar|from=Q131145}}

[[Category:Herrerasauridae]]
[[Category:Dinosaur genera]]
[[Category:Carnian dinosaurs]]
[[Category:Santa Maria Formation]]
[[Category:Taxa named by Edwin H. Colbert]]
[[Category:Fossil taxa described in 1970]]
[[Category:Dinosaurs of Brazil]]