Aetosaurs are heavily armored reptiles belonging to the extinct order Aetosauria. They were medium- to large-sized omnivorous or herbivorous pseudosuchians, part of the branch of archosaurs more closely related to crocodilians than to birds and other dinosaurs. All known aetosaurs are restricted to the Late Triassic, and in some strata from this time they are among the most abundant fossil vertebrates. They have small heads, upturned snouts, erect limbs, and a body ornamented with four rows of plate-like osteoderms. Aetosaur fossil remains are known from Europe, North and South America, parts of Africa, and India. Since their armoured plates are often preserved and are abundant in certain localities, aetosaurs serve as important Late Triassic tetrapod index fossils. Many aetosaurs had wide geographic ranges, but their stratigraphic ranges were relatively short. Therefore, the presence of particular aetosaurs can accurately date a site in which they are found.
Venaticosuchus is a genus of pseudosuchian archosaurs from the family Ornithosuchidae. Known from a single species, Venaticosuchus rusconii, this genus is described based on an incomplete skull and jaw collected from the Late Triassic (Carnian) Ischigualasto Formation in the Ischigualasto-Villa Unión Basin in northwestern Argentina, which was deposited around 230 million years ago. This fossil material has been termed the holotype specimen PVL 2578. Venaticosuchus incorporated a myriad of features present in the other two genera of ornithosuchids, Ornithosuchus and Riojasuchus. However, it also had several unique traits, relating to the lower jaw.
Gracilisuchus is an extinct genus of tiny pseudosuchian from the Late Triassic of Argentina. It contains a single species, G. stipanicicorum, which is placed in the clade Suchia, close to the ancestry of crocodylomorphs. Both the genus and the species were first described by Alfred Romer in 1972.
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 and Italy; A. crassicauda from Germany; and A. arcuatus from eastern North America. Additional specimens referred to Aetosaurus have been found in the Chinle Group of the southwestern United States, and the Fleming Fjord Formation of Greenland. Specimens of Aetosaurus occur in Norian-age strata.
Stagonolepis is an extinct genus of stagonolepidid aetosaur known from the Late Triassic Hassberge Formation of Germany, the Drawno Beds of Poland, and the Lossiemouth Sandstone of Scotland. Supposed fossils from North and South America have been placed into their own genera, Calyptosuchus and Aetosauroides, respectively.
Desmatosuchus is an extinct genus of archosaur belonging to the Order Aetosauria. It lived during the Late Triassic.
The Santa Maria Formation is a sedimentary rock formation found in Rio Grande do Sul, Brazil. It is primarily Carnian in age, and is notable for its fossils of cynodonts, "rauisuchian" pseudosuchians, and early dinosaurs and other dinosauromorphs, including the herrerasaurid Staurikosaurus, the basal sauropodomorphs Buriolestes and Saturnalia, and the lagerpetid Ixalerpeton. The formation is named after the city of Santa Maria in the central region of Rio Grande do Sul, where outcrops were first studied.
Typothorax is an extinct genus of typothoracine aetosaur that lived in the Late Triassic. Its remains have been found in North America. Two species are known: T. coccinarum, the type species, and T. antiquum.
Coahomasuchus is an extinct genus of aetosaurine aetosaur. Remains of the genus have been found from deposits in Texas and North Carolina that date to the Otischalkian faunachron of the Late Triassic. It was small for an aetosaur, being less than 1.5 metres long. The dorsal plates are distinctively flat and unflexed, and have a faint sub-parallel to radial ornamentation. The genus lacked spines or keels on these plates, features seen in many other aetosaurs. Coahomasuchus was very similar in appearance to the closely related Aetosaurus.
Rioarribasuchus is a genus of aetosaur. Fossils have been found from the Chinle Formation in Arizona and New Mexico that date back to the upper Late Carnian stage of the Late Triassic.
Lucasuchus is an extinct genus of aetosaur. Fossils have been found from the Bull Canyon Formation of the Dockum Group outcropping in the Revuelto Creek locality in Quay County, New Mexico. All specimens date back to the Norian stage of the Late Triassic. The genus was named in 1995 after the American paleontologist Spencer G. Lucas.
Tecovasuchus is an extinct genus of aetosaur. It is known primarily from osteoderms found from the Tecovas Formation in Texas, which is Late Triassic in age, dating back to the lower Norian. Material is also known from several other localities of the Chinle Group in New Mexico and Arizona, such as older Carnian outcrops and younger Rhaetian outcrops. Specimens of Tecovasuchus have been collected from the Tecovas Formation, the Bluewater Creek Formation, and the Los Esteros Member of the Santa Rosa Formation.
Aetosaurinae is one of the two main clades of aetosaurs, 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.
Desmatosuchinae is a major subfamily of aetosaurs within the clade Desmatosuchia. It is a stem-based taxon defined as all aetosaurs more closely related to Desmatosuchus than to Stagonolepis,Aetosaurus, or Paratypothorax.
Aetobarbakinoides is an extinct genus of stagonolepidid aetosaur known from the Late Triassic of Rio Grande do Sul state, southern Brazil. Fossils have been found from the Santa Maria Supersequence of the late Carnian and early Norian stages, making Aetobarbakinoides one of the oldest aetosaurs. The type species, A. brasiliensis, was named in 2012, and is notable for being described primarily by features of the vertebrae; most other aetosaurs are diagnosed by features in bony plates called osteoderms, which are by far the most common material. Although placed in a basal phylogenetic position among aetosaurs, Aetobarbakinoides is closely related to both desmatosuchines and typothoracisines, two derived clades of aetosaurs.
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, Erpetosuchus sp. from the Late Triassic of eastern United States and Parringtonia gracilis from the middle Middle Triassic of Tanzania; the group might also include Dyoplax arenaceus from the Late Triassic of Germany, Archeopelta arborensis and Pagosvenator candelariensis from Brazil and Tarjadia ruthae from Argentina.
Polesinesuchus is an extinct genus of stagonolepidid aetosaur known from the Late Triassic of southern Brazil. Fossils have been found from the Santa Maria Supersequence of the late Carnian and early Norian stages, making Polesinesuchus one of the oldest aetosaurs. It contains a single species, Polesinesuchus aurelioi, the fifth aetosaur species known from South America to date. Anatomical evidence suggests that Polesinesuchus likely represents a juvenile individual of the contemporary Aetosauroides.
Gorgetosuchus is an extinct genus of aetosaur from the Late Triassic of the North Carolina, represented by the type species Gorgetosuchus pekinensis. It is mainly known from osteoderms, including the front half of an articulated carapace. Gorgotesuchus is typically considered a basal desmatosuchin, though alternative interpretations exist.
Martín Dário Ezcurra is an Argentinian born palaeontologist naming many extinct genera such as Aerotitan, Lophostropheus and Powellvenator.
