Polesinesuchus

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.^[1] Anatomical evidence suggests that Polesinesuchus likely represents a juvenile individual of the contemporary Aetosauroides.^[2][3]

caudal vertebrae, both scapulae, a humerus, the ilium, pubis, ischium and tibia, a partial right pes, and anterior and mid-dorsal paramedian osteoderms. It was collected from the Santa Maria Formation which dates back to the late Carnian and earliest Norian stages of the Late Triassic.^[1]

centra of the anterior and mid-dorsal vertebrae lack a lateral fossa. The proximal end of the scapula is greatly expanded, while the medial portion of scapular blade is expanded anteroposteriorly. Polesinesuchus possess a short humerus with a robust shaft, and a dorsoventral and very low iliac blade with a long anterior process, exceeding slightly the pubic peduncle.^[1] Yet, in 2021, it was found that many of these features fall within the range of variation present in juvenile specimens of Aetosauroides. One example is the lateral fossa, which becomes more apparent in individuals of Aetosauroides longer than 1 metre (3 ft 3 in)).^[2] Furthermore, a braincase of Aetosauroides had a remarkably similar structure of the basioccipital bone to Polesinesuchus.^[3] For these reasons, Polesinesuchus was suggested as a junior synonym of Aetosauroides.^[2]

typothoracisines, two derived clades of stagonolepidids. Below is a cladogram modified from this analysis.^[1]