New specimens of Saturnalia tupiniquim (Dinosauria: Sauropodomorpha): insights into intraspecific variation, rostral anatomy, and skull size

Abstract

Dinosaurs arose in the Late Triassic and diversified during the subsequent periods of the Mesozoic Era. The oldest unequivocal dinosaurs come from Carnian deposits of Brazil, Argentina, India, and Zimbabwe, with sauropodomorphs representing the bulk of this record. Saturnalia tupiniquim was described from Brazilian strata in 1999 as the first Carnian member of that group. Although several new species and specimens of coeval sauropodomorphs have been described in recent years, no new material has been formally assigned to that species. In this contribution, we describe an association of at least three partially preserved individuals of S. tupiniquim (UFSM 11660), which was excavated from the S. tupiniquim type-locality (Late Triassic of the Santa Maria Formation) and preserves cranial and postcranial elements, including the first rostrum known for the species. Assigned to S. tupiniquim according to several lines of evidence, the new specimen has a proportionally short rostrum, compared to that of coeval sauropodomorphs, providing evidence for a reduced skull in S. tupiniquim. In addition, we investigated the intraspecific variation in S. tupiniquim, highlighting the need to understand the morphological limits of such variations among the earliest dinosaurs, in order to properly explore their alpha diversity.