Anatomical Details of Aetosauria (Archosauria: Pseudosuchia) as Revealed by an Articulated Posterior Skeleton from the Upper Triassic Ischigualasto Formation, San Juan Province, Argentina

Researchers have uncovered significant anatomical details of Aetosauria, a group of early-diverging 'crocodile-line' archosaurs, through the study of an articulated posterior skeleton from the Upper Triassic Ischigualasto Formation in Argentina. The specimen, resembling but not definitively assignable to the genus Aetosauroides, reveals unique features such as robust body structure and a distinct tail morphology. Notably, it displays extensive appendicular armor and a well-preserved caudal ventral carapace, which consists of only two columns of ventral osteoderms and includes a large cloacal vent. The study also identifies a fusion of posterior ventral paramedian osteoderms into a single element, a previously undocumented characteristic in aetosaurs. These findings challenge existing understanding of aetosaur anatomy and paleobiology.

Heckert, A. B., Martínez, R. N., & Celeskey, M. D. (2021). Anatomical Details of Aetosauria (Archosauria: Pseudosuchia) as Revealed by an Articulated Posterior Skeleton from the Upper Triassic Ischigualasto Formation, San Juan Province, Argentina. Ameghiniana, 58(6). https://doi.org/10.5710/amgh.05.09.2021.3426