Aetosauriformes is an extinct clade of early-diverging

pseudosuchia Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Prior to ...

ns (the group of

archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avi ...

s that contains modern

crocodylia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period (Cenomanian stage) and are the closest living ...

ns and their

stem group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor ...

relatives). It includes the

aetosaur Aetosaurs () are heavily armored reptiles belonging to the extinct order Aetosauria (; from Greek, (aetos, "eagle") and (, "lizard")). They were medium- to large-sized omnivorous or herbivorous pseudosuchians, part of the branch of archosaurs ...

s, a group of heavily armoured and at least partially

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...

pseudosuchians, as well as the closely related genera ''

Acaenasuchus ''Acaenasuchus'' (meaning "thorn crocodile") is an extinct genus of pseudosuchians, endemic to what would be Arizona during the Late Triassic, existing for approximately . Discovery and naming The holotype, UCMP 139576 (a left(?) dorsal paramedi ...

'', '' Euscolosuchus'' and ''

Revueltosaurus ''Revueltosaurus'' ("Revuelto lizard") is an extinct genus of suchian pseudosuchian from Late Triassic (late Carnian to middle Norian stage) deposits of New Mexico, Arizona and North Carolina, United States. Many specimens, mostly teeth, have be ...

''.

Classification

Aetosauriformes was named in

2021 File:2021 collage V2.png, From top left, clockwise: the James Webb Space Telescope was launched in 2021; Protesters in Yangon, Myanmar following the coup d'état; A civil demonstration against the October 2021 coup in Sudan; Crowd shortly after t ...

by William G. Parker and colleagues, as part of a redescription of the species ''

Revueltosaurus callenderi ''Revueltosaurus'' ("Revuelto lizard") is an extinct genus of suchian pseudosuchian from Late Triassic (late Carnian to middle Norian stage) deposits of New Mexico, Arizona and North Carolina, United States. Many specimens, mostly teeth, have b ...

''. It is a

stem-based taxon Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a ''type'', which c ...

, defined as the most inclusive clade that contains '' Acaenasuchus geoffreyi'', ''

Aetosaurus ferratus ''Aetosaurus'' is an extinct genus of pseudosuchian reptile belonging to the order Aetosauria. It is generally considered to be the most primitive aetosaur. Three species are currently recognized: ''A. ferratus'', the type species from Germany ...

'', ''

Desmatosuchus spurensis ''Desmatosuchus'' (, from Greek δεσμός ''desmos'' 'link' + σοῦχος ''soûkhos'' 'crocodile') is an extinct genus of archosaur belonging to the Order Aetosauria. It lived during the Late Triassic. Description ''Desmatosuchus'' was ...

'' and ''Revueltosaurus callenderi'', but not ''

Erpetosuchus granti ''Erpetosuchus'' is an extinct genus of pseudosuchian from the Late Triassic. The type species of ''Erpetosuchus'' is ''E. granti''. It was first described by E. T. Newton in 1894 for remains found in northeastern Scotland, including four speci ...

'', ''

Ornithosuchus woodwardi ''Ornithosuchus'' (meaning "bird crocodile") is an extinct genus of pseudosuchians from the Late Triassic ( Carnian) Lossiemouth Sandstone of Scotland. It was originally thought to be the ancestor to the carnosaurian dinosaurs (such as '' Allo ...

'', '' Poposaurus gracilis'', ''

Postosuchus kirkpatricki ''Postosuchus'', meaning "Crocodile from Post", is an extinct genus of rauisuchid reptiles comprising two species, ''P. kirkpatricki'' and ''P. alisonae'', that lived in what is now North America during the Late Triassic. ''Postosuchus'' is a ...

'', ''

Rutiodon carolinensis ''Rutiodon'' ("Wrinkle tooth") is an extinct genus of phytosaur belonging to the family Parasuchidae. It lived during the Late Triassic period, and was about in length. ''Rutiodon'' is known from the eastern United States (North Carolina, New Je ...

'', ''

Crocodylus niloticus ''Crocodylus'' is a genus of true crocodiles in the family Crocodylidae. Taxonomy The generic name, ''Crocodylus'', was proposed by Josephus Nicolaus Laurenti in 1768. ''Crocodylus'' contains 13–14 extant (living) species and 5 extinct sp ...

'' (the Nile crocodile) or ''

Passer domesticus The house sparrow (''Passer domesticus'') is a bird of the sparrow family Passeridae, found in most parts of the world. It is a small bird that has a typical length of and a mass of . Females and young birds are coloured pale brown and grey, an ...

'' (the house sparrow). Parker and colleagues performed a

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis using a modified version of the data matrix of Nesbitt ''et al.'' (2011). Aetosauriformes was recovered as the sister group of the family

Erpetosuchidae Erpetosuchidae is an extinct family of pseudosuchian archosaurs. Erpetosuchidae was named by D. M. S. Watson in 1917 to include ''Erpetosuchus''. It includes the type species ''Erpetosuchus granti'' from the Late Triassic of Scotland, ''Erpetosuc ...

, with the two groups forming the earliest-diverging clade within

Suchia Suchia is a clade of archosaurs containing the majority of pseudosuchians (crocodilians and their extinct relatives). It was defined as the least inclusive clade containing ''Aetosaurus ferratus'', '' Rauisuchus tiradentes'', '' Prestosuchus ch ...

. A simplified

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

from that study is shown below:

References

Suchians Tetrapod unranked clades Late Triassic reptiles Late Triassic first appearances Late Triassic extinctions Taxa named by Sterling Nesbitt Taxa named by Michelle R. Stocker {{Triassic-reptile-stub