Desmatosuchinae is one of the two subfamilies of aetosaur

Aetosaur

Aetosaurs are an extinct order of heavily armoured, medium- to large-sized Late Triassic herbivorous archosaurs. They have small heads, upturned snouts, erect limbs, and a body covered by plate-like scutes. All aetosaurs belong to the family Stagonolepididae...

s, the other being Aetosaurinae

Aetosaurinae

Aetosaurinae is one of the two subfamilies of aetosaurs, the other being Desmatosuchinae. It is a stem-based taxon defined as all aetosaurs more closely related to Aetosaurus than to the last common ancestor of Aetosaurus and Desmatosuchus. The only synapomorphy that diagnoses the clade...

. It is a stem-based taxon defined as all aetosaurs more closely related to Desmatosuchus

Desmatosuchus

Desmatosuchus is an extinct genus of archosaur belonging to the Order Aetosauria. It was one of the largest aetosaurs, being long and about 1.50 m high. It lived during the Late Triassic in Texas....

than the last common ancestor of Desmatosuchus and Stagonolepis

Stagonolepis

Stagonolepis is an extinct genus of aetosaur. It was about long.An aetosaur, Stagonolepis was a quadrupedal animal covered in thick armoured scales that ran down the length of the its body. A slow-moving browser, it would have used this heavy body armour to repel attacks from contemporary...

. All synapomorphies that diagnose the clade can be found in the osteoderm

Osteoderm

Osteoderms are bony deposits forming scales, plates or other structures in the dermal layers of the skin. Osteoderms are found in many groups of extant and extinct reptiles, including lizards, various groups of dinosaurs , crocodilians, phytosaurs, aetosaurs, placodonts, and hupehsuchians...

s. These include tongue-and-groove articulations for lateral plates present in dorsal presacral paramedian plates and large spikes on the lateral cervical, dorsal, and caudal plates.