Editing Archosaur (section)

{{short description|Group of diapsids broadly classified as reptiles}}
{{Automatic taxobox
| name = Archosaurs
| fossil_range = <br />[[Early Triassic]]&ndash;[[Holocene|Present]], {{Fossil range|248|earliest=251|0|ref=<ref>{{cite journal|author1=Richard J. Butler |author2=Stephen L. Brusatte |author3=Mike Reich |author4=Sterling J. Nesbitt |author5=Rainer R. Schoch |author6=Jahn J. Hornung |year=2011 |title=The sail-backed reptile ''Ctenosauriscus'' from the latest Early Triassic of Germany and the timing and biogeography of the early archosaur radiation |journal=PLOS ONE |volume=6 |issue=10 |pages=e25693 |doi=10.1371/journal.pone.0025693 |pmid=22022431 |pmc=3194824|bibcode=2011PLoSO...625693B |doi-access=free }}</ref>}}
| image = Crocodile Front Egret Kabini Nagarhole Apr22 D72 23712.jpg
| image_caption = Birds and crocodilians (in this case, a [[great egret]] and a [[mugger crocodile]]) are the only living archosaur groups.
| taxon = Archosauria
| authority = [[Edward Drinker Cope|Cope]], 1869
| subdivision_ranks = Subgroups
| subdivision = * [[Avemetatarsalia]] <br /><small>([[bird]]s and their extinct relatives)</small>
* [[Pseudosuchia]] <br /><small>([[crocodilia]]ns and their extinct relatives)</small>
{{Collapse top|title=Archosaurs of<br>uncertain affinity|left=yes|padding=0|border=0|border2=0|bg=clear|bg2=clear}}
* {{extinct}}''[[Albisaurus]]''
* {{extinct}}''[[Avalonianus]]''
* {{extinct}}''[[Avipes]]''
* {{extinct}}''[[Incertovenator]]''?
* {{extinct}}''[[Jushatyria]]''
* {{extinct}}''[[Palaeosaurus]]''
* {{extinct}}''[[Picrodon]]''
* {{extinct}}''[[Protecovasaurus]]''?
* {{extinct}}''[[Sikannisuchus]]''
* {{extinct}}''[[Smok (archosaur)|Smok]]''
* {{extinct}}''[[Zanclodon]]''
* {{extinct}}[[Phytosauria]]?([[Paraphyly|paraphyletic]]?)<ref>{{cite journal |title=Unappreciated diversification of stem archosaurs during the Middle Triassic predated the dominance of dinosaurs |year=2016 |publisher=Christian Foth, Martín D. Ezcurra, Roland B. Sookias, Stephen L. Brusatte and Richard J. Butler. |pmc=5024528 |ref=42|last1=Foth |first1=C. |last2=Ezcurra |first2=M. D. |last3=Sookias |first3=R. B. |last4=Brusatte |first4=S. L. |last5=Butler |first5=R. J. |journal=BMC Evolutionary Biology |volume=16 |issue=1 |page=188 |doi=10.1186/s12862-016-0761-6 |pmid=27628503 |bibcode=2016BMCEE..16..188F |doi-access=free }}</ref>
{{collapse bottom}}
| synonyms = *Avesuchia <small>Benton, 1999</small>
}}

'''Archosauria''' ({{lit|ruling reptiles}}) or '''archosaurs''' ({{IPAc-en|ˈ|ɑːr|k|ə|ˌ|s|ɔːr}}<ref>{{cite web|url=https://www.dictionary.com/browse/archosaur |title=Archosaur Definition & Meaning |publisher=Dictionary.com |date= |accessdate=2022-03-01}}</ref>) is a [[clade]] of [[diapsid]] [[sauropsid]] [[tetrapod]]s, with [[birds]] and [[crocodilian]]s being the only [[extant taxon|extant]] representatives. Although broadly classified as [[reptile]]s, which traditionally exclude birds, the [[cladistics|cladistic]] sense of the term includes all living and [[extinct]] relatives of birds and crocodilians such as [[non-avian dinosaur]]s, [[pterosaur]]s, [[phytosaur]]s, [[aetosaur]]s and [[rauisuchian]]s as well as many [[marine reptile#Extinct groups|Mesozoic marine reptiles]]. Modern paleontologists define Archosauria as a [[crown group]] that includes the [[most recent common ancestor]] of living birds and crocodilians, and all of its descendants.

The base of Archosauria splits into two clades: [[Pseudosuchia]], which includes crocodilians and their extinct relatives; and [[Avemetatarsalia]], which includes birds and their extinct relatives (such as non-avian dinosaurs and pterosaurs).<ref name="NSJ11" /> Older definitions of the group Archosauria rely on shared [[morphology (biology)|morphological]] characteristics, such as an [[antorbital fenestra]] in the skull, [[serration|serrated]] teeth, and an upright stance. Some extinct reptiles, such as [[proterosuchid]]s and [[euparkeriid]]s, also possessed these features yet originated prior to the split between the crocodilian and bird lineages. The older morphological definition of Archosauria nowadays roughly corresponds to [[Archosauriformes]], a group named to encompass crown-group archosaurs and their close relatives.<ref name="NSJ11" />

The oldest true archosaur [[fossil]]s are known from the [[Early Triassic]] period, though the first [[archosauriform]]s and [[archosauromorph]]s (reptilians closer to archosaurs than to [[lizard]]s or other [[lepidosaur]]s) appeared in the [[Permian]]. Archosaurs quickly diversified in the aftermath of the [[Permian-Triassic mass extinction]] (~252 [[mega-annum|Ma]]), which wiped out most of the then-[[dominance (ecology)|dominant]] [[therapsid]] competitors such as the [[gorgonopsian]]s and [[anomodont]]s, and the subsequent arid Triassic climate allowed the more [[drought]]-resilient archosaurs (largely due to their [[uric acid]]-based [[urinary system]]) to eventually become the largest and most ecologically dominant terrestrial vertebrates from the [[Middle Triassic]] period up until the [[Cretaceous–Paleogene extinction event]] (~66 Ma).<ref name="ESB14">{{cite journal|last1=Ezcurra|first1=M. N. D.|last2=Scheyer|first2=T. M.|last3=Butler|first3=R. J.|year=2014|title=The Origin and Early Evolution of Sauria: Reassessing the Permian Saurian Fossil Record and the Timing of the Crocodile-Lizard Divergence|journal=PLOS ONE|volume=9|issue=2|pages=e89165|doi=10.1371/journal.pone.0089165|pmc=3937355|pmid=24586565|bibcode=2014PLoSO...989165E|doi-access=free}}</ref> Birds and several [[crocodyliform]] lineages were the only archosaurs to survive the [[K-Pg]] extinction, rediversifying in the subsequent [[Cenozoic]] era. Birds in particular have become among the most species-rich groups of terrestrial vertebrates in the present day.