Aetosaurinae

{{Short description|Extinct subfamily of reptiles}} {{Automatic taxobox | name = Aetosaurinae | fossil_range = [[Late Triassic]] | image = Aetosaurus many specimens.jpg | image_caption = A [[bonebed]] of ''[[Aetosaurus]]'' | image2 = Paratypothorax andressorum.JPG | image2_caption = ''[[Paratypothorax]]'', a [[typothoracine]] | taxon = Aetosaurinae | authority = Heckert and Lucas, [[2000 in paleontology|2000]] | subdivision_ranks = [[Clade]]s | subdivision = *{{extinct}}''[[Aetosaurus]]'' *{{extinct}}''[[Coahomasuchus]]'' *{{extinct}}''[[Stenomyti]]'' *{{extinct}}'''Typothoracinae''' **{{extinct}}''[[Apachesuchus]]'' **{{extinct}}''[[Chilenosuchus]]''? **{{extinct}}''[[Gorgetosuchus]]'' **{{extinct}}''[[Kryphioparma]]'' **{{extinct}}''[[Redondasuchus]]'' **{{extinct}}''[[Typothorax]]'' **{{extinct}}'''Paratypothoracini''' ***{{extinct}}''[[Kocurypelta]]'' ***{{extinct}}''[[Kuttysuchus]]'' ***{{extinct}}''[[Paratypothorax]]'' ***{{extinct}}''[[Rioarribasuchus]]'' ***{{extinct}}''[[Tecovasuchus]]'' ***{{extinct}}''[[Venkatasuchus]]'' }}

'''Aetosaurinae''' is one of the two main clades of [[aetosaur]]s, the other being [[Desmatosuchia]]. It is a [[stem-based taxon]] defined as all aetosaurs more closely related to ''[[Aetosaurus]]'' than ''[[Desmatosuchus]]''. Aetosaurinae currently comprises ''Aetosaurus,'' similar forms such as ''[[Coahomasuchus]]'' and ''[[Stenomyti]]'', and the widespread and successful aetosaur clade [[Typothoracinae]].<ref name=":0" />

== Previous usage == Aetosaurinae was originally named in 2000, as a [[subfamily]] solely including ''Aetosaurus'', which was assumed to be the earliest-diverging aetosaur.<ref name="HL00">{{cite journal|last=Heckert|first=A. B.|author2=and Lucas|author3=S. G.|year=2000|title=Taxonomy, phylogeny, biostratigraphy, biochronology, paleobiogeography, and evolution of the Late Triassic Aetosauria (Archosauria: Crurotarsi).|url=https://www.academia.edu/1175956|journal=Zentralblatt für Geologie und Paläontologie, Teil I|volume=11-12|pages=1539–1587}}</ref> In 2007, it was extended to include the subfamily Typothoracinae as well as various [[Basal (phylogenetics)|basal]] aetosaurs which were not clearly within [[Desmatosuchinae]]. These proposed non-typothoracine aetosaurines included ''Coahomasuchus'', ''[[Neoaetosauroides]]'', ''[[Aetosauroides]]'', ''[[Stagonolepis|Stagonolepis robertsoni]],'' and ''"Stagonolepis"'' (''[[Calyptosuchus]]'') ''wellesi''. As a subfamily containing practically all non-desmatosuchine aetosaurs, Aetosaurinae was poorly supported. It was diagnosed by a singly [[synapomorphy]]: the dorsal eminence of each paramedian [[osteoderm]] was offset medially.<ref name="PWG07">{{cite journal|last=Parker|first=W. G.|year=2007|title=Reassessment of the aetosaur '''Desmatosuchus' chamaensis'' with a reanalysis of the phylogeny of the Aetosauria (Archosauria:Pseudosuchia)|url=http://www.miketaylor.org.uk/dino/nm/Parker2007-Heliocanthus.pdf|journal=Journal of Systematic Palaeontology|volume=5|pages=41–68|doi=10.1017/S1477201906001994|s2cid=85826683}}</ref><ref>{{Cite journal|last1=Parker|first1=William G.|last2=Stocker|first2=Michelle R.|last3=Irmis|first3=Randall B.|date=2008-09-12|title=A new desmatosuchine aetosaur (Archosauria: Suchia) from the Upper Triassic Tecovas Formation (Dockum Group) of Texas|url=https://www.researchgate.net/publication/272152066|journal=Journal of Vertebrate Paleontology|volume=28|issue=3|pages=692–701|doi=10.1671/0272-4634(2008)28[692:ANDAAS]2.0.CO;2|s2cid=84455880 |issn=0272-4634}}</ref>

A phylogenetic study in 2012 found that this widest usage of Aetosaurinae was [[paraphyletic]]. ''Aetosaurus'' was recovered as the basal-most stagonolepidid, with other non-typothoracisine aetosaurines placed as successively more [[Synapomorphy|derived]] taxa leading up to a clade containing Desmatosuchinae and Typothoracisinae. In this phylogeny, all aetosaurines except for ''Aetosaurus'' were more closely related to ''Desmatosuchus'' than they are to ''Aetosaurus.'' As a result, the clade Aetosaurinae would only include ''Aetosaurus''.<ref name="DEK12">{{cite journal|last=Desojo|first=J.B.|author2=Ezcurra, M.D.|author3=Kischlat, E.E.|year=2012|title=A new aetosaur genus (Archosauria: Pseudosuchia) from the early Late Triassic of southern Brazil|url=https://www.researchgate.net/publication/280386026|journal=Zootaxa|volume=3166|pages=1–33|doi=10.11646/zootaxa.3166.1.1|issn=1175-5326}}</ref><ref>{{Cite journal|last1=Heckert|first1=Andrew B.|last2=Schneider|first2=Vincent P.|last3=Fraser|first3=Nicholas C.|last4=Webb|first4=Richard A.|date=2015-01-02|title=A new aetosaur (Archosauria, Suchia) from the Upper Triassic Pekin Formation, Deep River Basin, North Carolina, U.S.A., and its implications for early aetosaur evolution|journal=Journal of Vertebrate Paleontology|volume=35|issue=1|article-number=e881831|doi=10.1080/02724634.2014.881831|bibcode=2015JVPal..35E1831H |s2cid=140176110|issn=0272-4634}}</ref>

== Current usage == More recent data and phylogenies have brought Aetosaurinae back into usage, albeit in a more restricted form. A 2016 study once again considered Typothoracinae to be closer to ''Aetosaurus'' than to desmatosuchines. Therefore, Typothoracinae would lie within Aetosaurinae, making Aetosaurinae a valid and non-[[Monotypic taxon|monotypic]] clade once more.<ref name=":0">{{Cite journal|last=Parker|first=William G.|date=2016-01-21|title=Revised phylogenetic analysis of the Aetosauria (Archosauria: Pseudosuchia); assessing the effects of incongruent morphological character sets|journal=PeerJ|language=en|volume=4|article-number=e1583|doi=10.7717/peerj.1583|pmid=26819845|pmc=4727975|issn=2167-8359|doi-access=free}}</ref> Newly described or redescribed genera such as ''Stenomyti'' and ''Coahomasuchus'' have also been incorporated into Aetosaurinae.<ref name=":0" /><ref>{{Cite journal|last1=Hoffman|first1=Devin K.|last2=Heckert|first2=Andrew B.|last3=Zanno|first3=Lindsay E.|date=2018-02-13|title=Under the armor: X-ray computed tomographic reconstruction of the internal skeleton of Coahomasuchus chathamensis (Archosauria: Aetosauria) from the Upper Triassic of North Carolina, USA, and a phylogenetic analysis of Aetosauria|journal=PeerJ|language=en|volume=6|article-number=e4368|doi=10.7717/peerj.4368|pmid=29456892|pmc=5815331|issn=2167-8359|doi-access=free}}</ref> Aetosaurinae is the [[sister taxon]] to Desmatosuchia, a new clade including desmatosuchines and their relatives, such as ''Stagonolepis''.<ref name=":0" />

Relative to desmatosuchians, aetosaurines have proportionally shorter and more lightly built skulls, as well as several other distinctive traits. The [[Orbit (anatomy)|orbit]] is large and circular, while the [[supratemporal fenestrae]] are fairly small. This also means that the [[Parietal bone|parietals]] are wider than the [[Frontal bone|frontals]] on the skull roof, at least in early-diverging genera such as ''Aetosaurus'' and ''Stenomyti''. The [[nares]] are similar in size or smaller than the orbit. The snout tapers to a point, without the "shovel-shaped" [[premaxilla]] extensions found in ''Stagonolepis'' and ''[[Desmatosuchus]]''.<ref name=":0" /><ref>{{Cite journal|last1=Reyes|first1=William A.|last2=Parker|first2=William G.|last3=Marsh|first3=Adam D.|date=2020-12-10|title=Cranial anatomy and dentition of the aetosaur ''Typothorax coccinarum'' (Archosauria: Pseudosuchia) from the Upper Triassic (Revueltian–mid Norian) Chinle Formation of Arizona|journal=Journal of Vertebrate Paleontology|volume=40|issue=6|article-number=e1876080|doi=10.1080/02724634.2020.1876080|bibcode=2020JVPal..40E6080R |s2cid=233616969|issn=0272-4634}}</ref>

==References== {{Portal|Paleontology}} {{Reflist}}

[[Category:Aetosauria]]