A saurischian (Archosauria, Dinosauria) ilium from the Upper Triassic of southern Brazil and the rise of Herrerasauria

Abstract

The Carnian (Upper Triassic) rocks of the Candelária Sequence present a rich record of dinosaurs, including some of the oldest known dinosaurs worldwide. In this contribution we describe the first unequivocal dinosaur from the Pivetta site, located in the Restinga Sêca municipality, Southern Brazil. The specimen CAPPA/UFSM 0373 is an isolated but well‐preserved left ilium. A thorough examination of the specimen's anatomy and a phylogenetic analysis provides evidence that CAPPA/UFSM 0373 belongs to the Herrerasauria. We were able to identify several similarities with potential non‐herrerasaurid herrerasaurians (e.g., Tawa hallae, “Caseosaurus crosbyensis”), which were previously only known from North American deposits. In contrast, herrerasaurids (e.g., Herrerasaurus ischigualastensis) are almost exclusively known from South America. Our results support the nesting of CAPPA/UFSM 0373 as an early‐diverging herrerasaurian. Furthermore, this is potentially the first record of a non‐herrerasaurid herrerasaurian in unambiguous Carnian beds, suggesting a hidden diversity of dinosaurs in the Carnian rocks of the Candelária Sequence, which can be revealed even by fragmentary specimens.

The dawn of an Era: New contributions on comparative and functional anatomy of Triassic tetrapods

“…Within this temporal window, we find the early records of lineages such as sauropodomorphs, herrerasaurids, and theropods. In this Special Issue, Garcia et al (2024, this issue) increase the early dinosaur diversity from Southern Brazil through the discovery of evidence indicating the presence of a non‐herrerasaurid herrerasaurian. Moro et al (2024, this issue) investigate how large the first sauropodomorphs could be based on a particularly robust specimen of Buriolestes schultzi .…”