''Coahomasuchus'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of aetosaurine

aetosaur Aetosaurs () are heavily armored reptiles belonging to the extinct order (biology), order Aetosauria (; from Ancient Greek, Greek, (aetos, "eagle") and (, "lizard")). They were medium- to large-sized Omnivore, omnivorous or Herbivore, herbivor ...

. Remains of the genus have been found from deposits in

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

and

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

that date to the Otischalkian faunachron (lower late

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

) of the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

. It was small for an aetosaur, being less than 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 ''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 a ...

''. Two species of ''Coahomasuchus'' are known. ''C. kahleorum'', the type species, was named by Heckert and Lucas in 1999; it is known from the Colorado City Formation of the

Dockum Group The Dockum is a Late Triassic (approximately late Carnian through Rhaetian, or 223–200 Ma) geologic group found primarily on the Llano Estacado of western Texas and eastern New Mexico with minor exposures in southwestern Kansas, eastern Color ...

. ''C. chathamensis'', a second species named by Heckert ''et al.'' in 2017, is from the

Pekin Formation The Pekin Formation is a Late Triassic (Carnian) geological Formation (geology), formation in North Carolina. The Pekin Formation is specific to the Sanford Sub-Basin of the Deep River Basin of North Carolina, although it may be equivalent to the ...

of the

Newark Supergroup The Newark Supergroup, also known as the Newark Group, is an assemblage of Upper Triassic and Lower Jurassic sedimentary and volcanic rocks which outcrop intermittently along the east coast of North America. They were deposited in a series of Tr ...

. The holotype of the latter species contains parts of the skull, which is rare among aetosaurs. ''C. chathamensis'' differs from ''C. kahleorum'' by wider osteoderms on the back and the underside of the neck, as well as the relative lengths of the processes of the

surangular The surangular or suprangular is a jaw bone found in most land vertebrates, except mammals. Usually in the back of the jaw, on the upper edge, it is connected to all other jaw bones: dentary, angular bone, angular, splenial and articular. It is o ...

References

External links

''Coahomasuchus''
at

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Aetosaurs of North America Prehistoric pseudosuchian genera {{triassic-reptile-stub