Braincase anatomy of the early sauropodomorph Saturnalia tupiniquim (Late Triassic, Brazil)

Author(s)

Bronzati, Mario ^{[1, 2, 3]} ; Langer, Max C. ^[2] ; Rauhut, Oliver W. M. ^{[1, 3]}

Affiliation

^[1] Bayer Staatssammlung Palaontol & Geol, D-80333 Munich - Germany

^[2] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Lab Paleontol, BR-14040901 Ribeirao Preto, SP - Brazil

^[3] Ludwig Maximilians Univ Munchen, Fac Geosci, D-80333 Munich - Germany

• Document type: Journal article
• Source: JOURNAL OF VERTEBRATE PALEONTOLOGY; v. 38, n. 5 MAR 2019.
• Web of Science Citations: 0

Abstract

The braincase anatomy of the sauropodomorph dinosaur Saturnalia tupiniquim from the Upper Triassic (Carnian) Santa Maria Formation of Brazil is described for the first time using computed tomography (CT). The braincase is characterized by a semilunar depression on the lateral surface of the basisphenoid, an occipital condyle whose ventral margin lies dorsal to the ventral margin of the cultriform process of the parabasisphenoid, a poorly developed preotic pendant, and anteriorly oriented basipterygoid processes. The comparative description improves our understanding of the early dinosaur braincase, which is poorly known relative to that of later representatives of the group. In addition, we discuss braincase features recently employed to investigate the phylogenetic relationships of dinosauromorphs, especially the pneumatic recesses of the braincase. Our study indicates that the semilunar depression and basioccipital recess are more widespread among dinosaurs and their closest archosauriform relatives than previously suggested. These structures are present in the three main dinosaurian lineages and also in non-dinosaurian dinosauromorphs, indicating that they might be plesiomorphic for Dinosauria. Likewise, the subsellar and basisphenoid recesses were observed in all examined dinosauromorph taxa, with variation observed in the relative development of these structures but not in their presence/absence. Our character reassessments and discussion of morphological variation as parts of transformation series strengthen the basis for integrating braincase features in future studies of dinosauromorph phylogeny. (AU)

• FAPESP's process: 14/03825-3 - The origin and rise of dinosaurs in Gondwana (late Triassic - early Jurassic)
• Grantee: Max Cardoso Langer
• Support Opportunities: Research Projects - Thematic Grants