Morphology of the endocranial cavities of Campinasuchus dinizi (Crocodyliformes: Baurusuchidae) from the Upper Cretaceous of Brazil

Abstract

Two specimens of Campinasuchus dinizi (CPPLIP 1319 and CPPLIP 1360) belonging to Baurusuchidae (Crocodyliformes, Notosuchia) from the Upper Cretaceous Bauru Group of Minas Gerais state (Brazil) were scanned in a Toshiba Aquilion 64 CT machine. Based on these data, it was possible to identify and reconstruct the paranasal sinuses, the nasal cavity proper, the nasopharyngeal duct, the encephalon, the paratympanic sinuses, and the semicircular canals of the inner ear. The paranasal sinuses present similar morphology to those of other mesoeucrocodylians, especially eusuchians. The nasal cavity proper occupies the entire rostral region, with an expansion in the olfactory region. The expansion in the nasal cavity is present in other notosuchians and theropod dinosaurs (e.g., Tyrannosaurus rex Osborn, 1905), but less developed in aquatic crocodilians, which may indicate an olfactory acuity related to terrestrial habits. The encephalon is similar in shape to that of other mesoeucrocodylians. The rostral semicircular canal is smaller than the caudal one, differing from most mesoeucrocodylians. The paratympanic sinuses are more developed in C. dinizi than in eusuchians, being more similar to Tyrannosaurus rex. Campinasuchus dinizi presents few variations in the internal structures of the skull in relation to taxa with different ecological niches, probably indicating that ecological factors do not strongly influence the morphology of these structures.