Aetosauroides is an extinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 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...

 from the Late Triassic

Late Triassic

The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...

 of South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. It is one of three aetosaurs known from South America, the others being Neoaetosauroides

Neoaetosauroides

Neoaetosauroides is an extinct genus of primitive aetosaur. Its type and only species is N. engaeus. Fossils have been found from the Los Colorados Formation outcropping along the Sierra Morada River in La Rioja, Argentina, and date back to the Norian age of the Late Triassic...

and Chilenosuchus

Chilenosuchus

Chilenosuchus is an extinct genus of aetosaur. Fossils have been found from the Antofagasta Region in northern Chile. The presence of Chilenoasaurus in the beds that it was found in conflicts with the inferred age of the strata...

. Two species have been named: the type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

 A. scaglia and a second called A. subsulcatus.

Aetosauroides was proposed to be synonymous with the genus 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...

in 1996 and 2002. Smaller specimens of both species were placed with Stagonolepis robertsoni, and larger specimens were considered to be S. wellesi. This synonymy is not entirely accepted, with several studies identifying unique features that distinguish Aetosauroides from Stagonolepis. Among these are maxilla

Maxilla

The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...

e that do not touch the nostrils, oval-shaped holes on the centra

Body of vertebra

The body is the largest part of a vertebra, and is more or less cylindrical in shape. For vertebrates other than humans, this structure is usually called a centrum....

 of the vertebrae, and a convex margin of the lower jaw. In a 2011 study, A. subsulcatus was proposed to be synonymous with A. scaglia.