Saturnalia tupiniquim - MCP3845PV
Project
ID: 00000C553
Public
The braincase anatomy of the sauropodomorph dinosaur Saturnalia tupiniquim from the Late Triassic (Carnian) Santa Maria Formation of Brazil is described for the first time, using information based on CT-Scan data. The braincase of Saturnalia tupiniquim is characterised by the presence of a semilunar depression on the lateral surface of the basisphenoid, an occipital condyle with the ventral margin located dorsally in relation to the ventral margin of the cultriform process of the parabasisphenoid, a poorly developed preotic pendant, and anteriorly-oriented basipterygoid processes. The comparative description fills a gap in the knowledge of braincase anatomy of early dinosaurs, still poorly known in comparison to the anatomy of later representatives of the group. In addition, we provide a discussion on 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 the basioccipital recess are more widespread among dinosaurs and their closest archosauriform relatives than previously suggested. These structures are found among members of the three main dinosaurian lineages and also in non-dinosaurian dinosauromorphs, indicating that they might represent the plesiomorphic condition in dinosaurs. Likewise, pneumatic recesses such as the subsellar and basisphenoid recesses were observed in all dinosauromorph taxa analysed for this study, with the variation concerning only the development of these structures rather than their absence/presence. The reassessment of previously proposed phylogenetic characters and the discussion of morphological variation as parts of transformation series provide a stronger basis for future studies on dinosauromorph phylogeny.