The nasals of the abelisaurid theropod Skorpiovenator bustingorryi and its biological implications.

CERRONI, M.A.; CANALE, J.I.; PAULINA-CARABAJAL, ARIANA; NOVAS, F.E.

Congreso; Reunion Anual de la Asociacion Palentologica Argentina; 2019

Abelisaurids were one of the most successful theropod clades during Cretaceous times. They are featured by numerous derived skull traits, such as heavily ornamented bones, short and tall snout, and a strongly thickened cranial roof. Furthermore, nasals are distinctive on having two distinct patterns, strongly convex (e.g., Carnotaurus Bonaparte, 1985) or concave (e.g., Rugops Sereno et al., 2004) in transverse section. Independently of the pattern, some abelisaurid nasals (e.g., Rugops) show a distinctive row of large foramina on the dorsal surface, which were in general associated to skin-structures (scales). CT scans of the skulls of Skorpiovenator Canale et al., 2008 and Carnotaurus indicate that these foramina are associated internally to a single and narrow canal that extends anteroposteriorly across each nasal bone. This canal is notably larger in diameter in Skorpiovenator. The symmetry and lateralized position of these canals and foramina would indicate a neurovascular origin. Regarding vasculature, they may represent branches of the lateral nasal blood vessel as in extant archosaurs. Whereas the cranial innervation may correspond to the ophthalmic branch of the trigeminal nerve (CN V1), which innervates nasals in living crocodiles and birds. The biological significance of such neurovascular system can be conjectured from several hypotheses. A possible one involves an enhanced blood volume linked to a zone of thermal exchange. However, other more speculative explanations like display skin-structures (in which higher blood volumes nourished the mineralized skin) and the correlation with integumentary sensory organs should not be discarded.