Aetosaur

Aetosaurs were heavily armoured reptiles in the extinct order Aetosauria. They were medium- to large-sized pseudosuchians. They were omnivorous or herbivorous

Aetosauria Temporal range: Upper Triassic, 231.4–201.3
Skeletal mount of Desmatosuchus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	†Aetosauriformes
Order:	†Aetosauria Lydekker, 1887
Subgroups
†Aetosauroides †Stagonolepididae Lydekker, 1887 sensu Heckert & Lucas, 2000 †Aetosaurinae †Stagonolepidoidea / Desmatosuchia Case, 1920 sensu Parker, 2016 †Desmatosuchinae †Stagonolepidinae Lydekker, 1887 sensu Heckert & Lucas, 2000 †Calyptosuchus? †Polesinesuchus †Stagonolepis

The aetosaurs were archosaurs more closely related to crocodilians than to dinosaurs. All known aetosaurs lived in the Upper Triassic. In some strata they are quite common.

They had small heads, upturned snouts, erect limbs, and a body ornamented with four rows of plate-like osteoderms (bony scutes). Aetosaur fossil remains are found in Europe, North and South America, parts of Africa, and India.

Since their armoured plates are often preserved and are common in certain places, aetosaurs serve as important Upper Triassic tetrapod index fossils. Many aetosaurs had wide geographic ranges, but they did not survive long. Their stratigraphic ranges were short. Therefore, the presence of particular aetosaurs accurately dates the site where they are found.^[1][2]

Over 20 genera of aetosaurs have been described. Two distinct subdivisions of aetosaurs are currently recognized, Desmatosuchia and Aetosaurinae, based primarily on broad differences in skull morphology. Osteoderms structure is generally one of the most useful traits for classification. Among other archosaurs, aetosaurs are most closely related to Revueltosaurus, a small reptile whose teeth were once mistaken for those of a herbivorous dinosaur.