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.
Chindesaurus is an extinct genus of basal saurischian dinosaur from the Late Triassic of the southwestern United States. It is known from a single species, C. bryansmalli, based on a partial skeleton recovered from Petrified Forest National Park in Arizona. The original specimen was nicknamed "Gertie", and generated much publicity for the park upon its discovery in 1984 and airlift out of the park in 1985. Other fragmentary referred specimens have been found in Late Triassic sediments throughout Arizona, New Mexico, and Texas, but these may not belong to the genus. Chindesaurus was a bipedal carnivore, approximately as large as a wolf.
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.
Calyptosuchus is an extinct genus of aetosaur from the Late Triassic of North America. Like other aetosaurs, it was heavily armored and had a pig-like snout used to uproot plants.
Acaenasuchus is an extinct genus of pseudosuchian, endemic to what would be presently be known as Arizona during the Late Triassic, specifically during the Carnian and Norian stages of the Triassic. Acaenasuchus had a stratigraphic range of approximately 11.5 million years. Acaenasuchus is further categorized as one of the type fauna that belong to the Adamanian LVF, based on the fauna of the Blue Mesa Member of the Chinle Petrified Forest Formation of Arizona, where Acaenasuchus was initially discovered.
Aetosauroides is an extinct genus of aetosaur from the Late Triassic of South America. It is one of four aetosaurs known from South America, the others being Neoaetosauroides, Chilenosuchus and Aetobarbakinoides. Three species have been named: the type species A. scagliai, A. subsulcatus and A. inhamandensis. Fossils have been found in the Cancha de Bochas Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin in northwestern Argentina and the Santa Maria Formation in the Paraná Basin in southeastern Brazil. The strata date to the late Carnian and early Norian stages, making Aetosauroides one of the oldest aetosaurs.
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.
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.
Paratypothorax is an extinct genus of aetosaur, known from a single species, Paratypothorax andressorum. It was a broadly distributed member of the group found in Germany, North America, and possibly parts of Gondwana. The best specimens come from Germany, though for more than a century they were mistakenly considered phytosaur armor. Paratypothorax was a large and wide-bodied typothoracine aetosaur, as well as the namesake of the tribe Paratypothoracisini.
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.
Redondasuchus is an extinct genus of aetosaur. It may be a junior synonym of Typothorax coccinarum, another aetosaur. Redondasuchus is a member of the clade Typothoracisinae within the subfamily Aetosaurinae, and lived during the middle Norian stage of the Late Triassic. Material belonging to the genus has been found from the Redonda Formation in east-central New Mexico. The type species, R. reseri, was named in 1991 after having been referred to as a species of Typothorax since 1985. A second species, R. rineharti, was described in 2006.
Tarjadia is an extinct genus of erpetosuchid pseudosuchian, distantly related to modern crocodilians. It is known from a single species, T. ruthae, first described in 1998 from the Middle Triassic Chañares Formation in Argentina. Partial remains have been found from deposits that are Anisian-Ladinian in age. Long known mostly from osteoderms, vertebrae, and fragments of the skull, specimens described in 2017 provided much more anatomical details and showed that it was a fairly large predator. Tarjadia predates known species of aetosaurs and phytosaurs, two Late Triassic groups of crurotarsans with heavy plating, making it one of the first heavily armored archosaurs. Prior to 2017, most studies placed it outside Archosauria as a member of Doswelliidae, a family of heavily armored and crocodile-like archosauriforms. The 2017 specimens instead show that it belonged to the Erpetosuchidae.
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.
Scutarx is an extinct genus of Aetosauriformes, most commonly regarded by its species name Scutarx deltatylus. Scutarx lived around 230 million years ago during the Carnian and Norian stage of the Late Triassic. Scutarx are “medium sized” paramedian osteoderms belonging to the clade Aetosauria, a heavily armored and more herbivorous cousin of crocodiles.
Apachesuchus is an extinct genus of aetosaur from the Late Triassic of New Mexico. It is only known from several paramedian osteoderms discovered in Quay County in eastern New Mexico. This area belongs to the late Norian-age Quay Member of the Redonda Formation. Unique among aetosaurs, its osteoderms are nearly completely smooth, without strong pits or grooves. The left dorsal paramedian has a relatively high width-to-length ration, suggesting that Apachesuchus is a wide-bodied aetosaur within the clade Typothoracinae.
Venkatasuchus is an extinct genus of aetosaur from the Late Triassic Dharmaram Formation of India. It was described in 2023 on the basis of a series of associated osteoderms that formed the paramedian and lateral armour. Based on the osteoderms the carapace of Venkatasuchus was disc-shaped and very wide, with curved, horn-like elements along its sides. Phylogenetic analysis indicates that Venkatasuchus belonged to the subfamily Typothoracinae and more specifically the clade Paratypothoracini, where it is recovered as the sister taxon to Kocurypelta. Venkatasuchus is among the few aetosaurs recovered from the region that would later become Gondwana and lends credence to the idea that late Triassic India represented a connective hub between Laurasian and Gondwanan fauna. The genus is monotypic, meaning it only includes a single species, Venkatasuchus armatum.
