The first braincase of the basal aetosaur Aetosauroides scagliai (Archosauria: Pseudosuchia) from the Upper Triassic of Brazil.

PAES-NETO, VOLTAIRE DUTRA; DESOJO, JULIA BRENDA; BIACCHI BRUST, ANA CAROLINA; RIBEIRO, A. M.; CESAR LEANDRO SCHULTZE; SOARES, M. B.

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Lugar: Lawrence; Año: 2021

0272-4634

The phylogenetic relationships of Pseudosuchia, the crocodile-line of Archosauria, are still poorly resolved, inpart, due to the lack of crucial braincase information for several key taxa. Recently, erpetosuchids and ornithosuchids havebeen recovered as close relatives to Aetosauria, sharing several braincase features. Here we provide the description of the firstbraincase of the basal aetosaur Aetosauroides based on specimens from the Upper Triassic Candelária Sequence of Brazil.Our study revealed the presence of an exoccipital lateral ridge and a medial ridge on the supraoccipital (both shared withall aetosaurs and erpetosuchids, but absent in ornithosuchids) and an anterolateral exit for the internal carotids (sharedwith all aetosaurs and ornithosuchids, but not with erpetosuchids). Aetosauroides lacks a medial contact between theexoccipitals (shared with the aetosaurs Desmatosuchus smalli and Tecovasuchus) and possesses a single hypoglossalforamen (contrasting with Stagonolepis robertsoni and Desmatosuchus spurensis). It also differs from the putativeArgentinian Aetosauroides (PVSJ 326) by the presence of a ridge connecting the basal tubera medially (contrasting alsowith all stagonolepidoideans) and by a bulbous and ventrolaterally recurved basipterygoid process (contrasting withParatypothorax). These features show that the braincase of aetosaurs is suitable for providing further phylogeneticinformation and may contribute to resolving controversies within Pseudosuchia relationships.