Editing Dinosaur (section)

===Origins and early evolution===
[[File:Herrerasaurusskeleton.jpg|thumb|alt=Full skeleton of an early carnivorous dinosaur, displayed in a glass case in a museum|The early dinosaurs ''[[Herrerasaurus]]'' (large), ''[[Eoraptor]]'' (small) and a ''[[Plateosaurus]]'' skull, from the [[Triassic]]]]
Dinosaurs diverged from their archosaur ancestors during the Middle to Late Triassic epochs, roughly 20&nbsp;million years after the devastating [[Permian–Triassic extinction event]] wiped out an estimated 96% of all marine species and 70% of terrestrial vertebrate species approximately 252&nbsp;million years ago.<ref name=KPA/><ref name=TannerLucas/> The oldest dinosaur fossils known from substantial remains date to the [[Carnian]] epoch of the Triassic period and have been found primarily in the [[Ischigualasto Formation|Ischigualasto]] and [[Santa Maria Formation]]s of Argentina and Brazil, and the [[Pebbly Arkose Formation]] of Zimbabwe.<ref name="griffin2022">{{cite journal |last1=Griffin |first1=C.T. |last2=Wynd |first2=B.M. |last3=Munyikwa |first3=D. |last4=Broderick |first4=T.J. |last5=Zondo |first5=M. |last6=Tolan |first6=S. |last7=Langer |first7=M.C. |last8=Nesbitt |first8=S.J. |last9=Taruvinga |first9=H.R. |year=2022 |title=Africa's oldest dinosaurs reveal early suppression of dinosaur distribution |journal=Nature |volume=609 |issue=7926 |pages=313–319 |doi=10.1038/s41586-022-05133-x |pmid=36045297 |bibcode=2022Natur.609..313G |s2cid=251977824 |issn=0028-0836}}</ref>

The Ischigualasto Formation ([[radiometric dating|radiometrically dated]] at 231–230 million years old<ref name="desojo2020">{{cite journal |last1=Desojo |first1=J.B. |last2=Fiorelli |first2=L.E. |last3=Ezcurra |first3=M.D. |last4=Martinelli |first4=A.G. |last5=Ramezani |first5=J. |last6=Da Rosa |first6=A.A.S. |last7=Belén von Baczko |first7=M. |last8=Jimena Trotteyn |first8=M. |last9=Montefeltro |first9=F.C. |last10=Ezpeleta |first10=M. |last11=Langer |first11=M.C. |year=2020 |title=The Late Triassic Ischigualasto Formation at Cerro Las Lajas (La Rioja, Argentina): fossil tetrapods, high-resolution chronostratigraphy, and faunal correlations |journal=Scientific Reports |volume=10 |issue=1 |page=12782 |doi=10.1038/s41598-020-67854-1 |pmid=32728077 |pmc=7391656 |bibcode=2020NatSR..1012782D}}</ref>) has produced the early saurischian ''[[Eoraptor]]'', originally considered a member of the [[Herrerasauridae]]<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]] |location=[[Sofia]] |publisher=[[Pensoft Publishers]] |issue=63 |pages=55–81 |doi=10.3897/zookeys.63.550 |pmc=3088398 |issn=1313-2989 |pmid=21594020|bibcode=2010ZooK...63...55A |doi-access=free}}</ref> but now considered to be an early sauropodomorph, along with the herrerasaurids ''Herrerasaurus'' and ''[[Sanjuansaurus]]'', and the sauropodomorphs ''[[Chromogisaurus]]'', ''[[Eodromaeus]]'', and ''[[Panphagia]]''.<ref name="novas2021">{{cite journal |last1=Novas |first1=F.E. |last2=Agnolin |first2=F.L. |last3=Ezcurra |first3=M.D. |last4=Müller |first4=R.T. |last5=Martinelli |first5=A. |last6=Langer |first6=M. |year=2021 |title=Review of the fossil record of early dinosaurs from South America, and its phylogenetic implications |journal=Journal of South American Earth Sciences |volume=110 |page=103341 |doi=10.1016/j.jsames.2021.103341 |issn=0895-9811 |bibcode=2021JSAES.11003341N}}</ref> ''Eoraptor''{{'s}} likely resemblance to the [[Common descent|common ancestor]] of all dinosaurs suggests that the first dinosaurs would have been small, bipedal [[predation|predators]].<ref name="Daemonosaurus">{{cite journal |last1=Nesbitt |first1=Sterling J |last2=Sues |first2=Hans-Dieter |title=The osteology of the early-diverging dinosaur ''Daemonosaurus chauliodus'' (Archosauria: Dinosauria) from the Coelophysis Quarry (Triassic: Rhaetian) of New Mexico and its relationships to other early dinosaurs |journal=Zoological Journal of the Linnean Society |date=2021 |volume=191 |issue=1 |pages=150–179 |doi=10.1093/zoolinnean/zlaa080|doi-access=free }}</ref><ref name=Sereno1999/><ref name=SFRM93/> The Santa Maria Formation (radiometrically dated to be older, at 233.23&nbsp;million years old<ref name=langer18>{{cite journal |last1=Langer |first1=Max C.|last2=Ramezani |first2=Jahandar |last3=Da Rosa |first3=Átila A.S. |title=U-Pb age constraints on dinosaur rise from south Brazil |date=May 2018 |journal=[[Gondwana Research]] |location=Amsterdam |publisher=Elsevier |volume=57 |pages=133–140 |doi=10.1016/j.gr.2018.01.005 |bibcode=2018GondR..57..133L |issn=1342-937X}}</ref>) has produced the herrerasaurids ''[[Gnathovorax]]'' and ''[[Staurikosaurus]]'', along with the sauropodomorphs ''[[Bagualosaurus]]'', ''[[Buriolestes]]'', ''[[Guaibasaurus]]'', ''[[Macrocollum]]'', ''[[Nhandumirim]]'', ''[[Pampadromaeus]]'', ''Saturnalia'', and ''[[Unaysaurus]]''.<ref name="novas2021"/> The Pebbly Arkose Formation, which is of uncertain age but was likely comparable to the other two, has produced the sauropodomorph ''[[Mbiresaurus]]'', along with an unnamed herrerasaurid.<ref name="griffin2022"/>

Less well-preserved remains of the sauropodomorphs ''[[Jaklapallisaurus]]'' and ''[[Nambalia]]'', along with the early saurischian ''[[Alwalkeria]]'', are known from the [[Upper Maleri Formation|Upper Maleri]] and [[Lower Maleri Formation]]s of India.<ref name="novas2011">{{cite journal |last1=Novas |first1=F.E. |last2=Ezcurra |first2=M.D. |last3=Chatterjee |first3=S. |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|bibcode=2010EESTR.101..333N |s2cid=128620874 }}</ref> The Carnian-aged [[Chañares Formation]] of Argentina preserves primitive, dinosaur-like ornithodirans such as ''[[Lagosuchus]]'' and ''[[Lagerpeton]]'' in [[Argentina]], making it another important site for understanding dinosaur evolution. These ornithodirans support the model of early dinosaurs as small, bipedal predators.<ref name="novas2021"/><ref name="mariscano2016">{{cite journal |last1=Marsicano |first1=C.A. |last2=Irmis |first2=R.B. |last3=Mancuso |first3=A.C. |last4=Mundil |first4=R. |last5=Chemale |first5=F. |year=2016 |title=The precise temporal calibration of dinosaur origins |journal=Proceedings of the National Academy of Sciences |volume=113 |issue=3 |pages=509–513 |doi=10.1073/pnas.1512541112|pmid=26644579 |pmc=4725541 |bibcode=2016PNAS..113..509M |doi-access=free }}</ref> Dinosaurs may have appeared as early as the [[Anisian]] epoch of the Triassic, approximately 243&nbsp;million years ago, which is the age of ''[[Nyasasaurus]]'' from the [[Manda Formation]] of Tanzania. However, its known fossils are too fragmentary to identify it as a dinosaur or only a close relative.<ref name=nyasasaurus>{{cite journal |last1=Nesbitt |first1=Sterling J. |last2=Barrett |first2=Paul M. |last3=Werning |first3=Sarah |last4=Sidor |first4=Christian A. |author-link4=Christian Sidor |last5=Charig |first5=Alan J. |author-link5=Alan J. Charig |display-authors=3 |year=2012 |title=The oldest dinosaur? A Middle Triassic dinosauriform from Tanzania |journal=[[Biology Letters]] |volume=9 |issue=1 |page=20120949 |location=London |publisher=Royal Society |doi=10.1098/rsbl.2012.0949 |issn=1744-9561 |pmc=3565515 |pmid=23221875}}</ref> The referral of the Manda Formation to the Anisian is also uncertain. Regardless, dinosaurs existed alongside non-dinosaurian ornithodirans for a period of time, with estimates ranging from 5–10 million years<ref name="marsicano2015">{{cite journal |last1=Marsicano |first1=C.A. |last2=Irmis |first2=R.B. |last3=Mancuso |first3=A.C. |last4=Mundil |first4=R. |last5=Chemale |first5=F. |year=2015 |title=The precise temporal calibration of dinosaur origins |journal=Proceedings of the National Academy of Sciences |volume=113 |issue=3 |pages=509–513 |doi=10.1073/pnas.1512541112 |pmid=26644579 |pmc=4725541 |bibcode=2016PNAS..113..509M |issn=0027-8424 |doi-access=free}}</ref> to 21 million years.<ref name="langer18"/>

When dinosaurs appeared, they were not the dominant terrestrial animals. The terrestrial habitats were occupied by various types of [[Archosauromorpha|archosauromorphs]] and [[therapsid]]s, like [[cynodont]]s and [[rhynchosaur]]s. Their main competitors were the [[pseudosuchians]], such as [[aetosaur]]s, [[ornithosuchidae|ornithosuchids]] and rauisuchians, which were more successful than the dinosaurs.<ref>{{cite journal |last1=Brusatte |first1=Stephen L. |author-link1=Stephen L. Brusatte |last2=Benton |first2=Michael J. |last3=Ruta |first3=Marcello |author-link3=Marcello Ruta |last4=Lloyd |first4=Graeme T. |year=2008 |title=Superiority, Competition, and Opportunism in the Evolutionary Radiation of Dinosaurs |url=https://www.pure.ed.ac.uk/ws/files/8232088/PDF_Brusatteetal2008SuperiorityCompetition.pdf |archive-url=https://web.archive.org/web/20180719005836/https://www.pure.ed.ac.uk/ws/files/8232088/PDF_Brusatteetal2008SuperiorityCompetition.pdf |archive-date=2018-07-19 |url-status=live |journal=Science |location=Washington, D.C. |publisher=American Association for the Advancement of Science |volume=321 |issue=5895 |pages=1485–1488 |doi=10.1126/science.1161833 |bibcode=2008Sci...321.1485B |issn=0036-8075 |pmid=18787166 |access-date=October 22, 2019|hdl=20.500.11820/00556baf-6575-44d9-af39-bdd0b072ad2b |s2cid=13393888 }}</ref> Most of these other animals became extinct in the Triassic, in one of two events. First, at about 215&nbsp;million years ago, a variety of [[Basal (phylogenetics)|basal]] archosauromorphs, including the [[Protorosauria|protorosaurs]], became extinct. This was followed by the Triassic–Jurassic extinction event (about 201&nbsp;million years ago), that saw the end of most of the other groups of early archosaurs, like aetosaurs, ornithosuchids, [[phytosaur]]s, and rauisuchians. Rhynchosaurs and [[dicynodont]]s survived (at least in some areas) at least as late as early –mid [[Norian]] and late Norian or earliest [[Rhaetian]] [[Stage (stratigraphy)|stage]]s, respectively,<ref>{{harvnb|Tanner|Spielmann|Lucas|2013|pp=[https://econtent.unm.edu/digital/collection/bulletins/id/1688 562–566]|loc="The first Norian (Revueltian) rhynchosaur: Bull Canyon Formation, New Mexico, U.S.A." by Justin A. Spielmann, Spencer G. Lucas and Adrian P. Hunt.}}</ref><ref>{{cite journal |last1=Sulej |first1=Tomasz |last2=Niedźwiedzki |first2=Grzegorz |year=2019 |title=An elephant-sized Late Triassic synapsid with erect limbs |journal=Science |location=Washington, D.C. |publisher=American Association for the Advancement of Science |volume=363 |issue=6422 |pages=78–80 |doi=10.1126/science.aal4853 |issn=0036-8075 |pmid=30467179|bibcode=2019Sci...363...78S |s2cid=53716186 |doi-access=free }}</ref> and the exact date of their [[extinction]] is uncertain. These losses left behind a land fauna of [[crocodylomorpha|crocodylomorphs]], dinosaurs, mammals, pterosaurians, and [[turtle]]s.<ref name=MJB04dino/> The first few lines of early dinosaurs [[Adaptive radiation|diversified]] through the Carnian and Norian stages of the Triassic, possibly by occupying the niches of the groups that became extinct.<ref name="Letal05"/> Also notably, there was a heightened rate of extinction during the [[Carnian pluvial episode|Carnian pluvial event]].<ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |date=April 19, 2018 |title=Fossil tracks in the Alps help explain dinosaur evolution |url=https://www.economist.com/science-and-technology/2018/04/19/fossil-tracks-in-the-alps-help-explain-dinosaur-evolution |url-access=registration |department=Science and Technology |newspaper=[[The Economist]] |location=London |issn=0013-0613 |access-date=May 24, 2018}}</ref>