The skull of Skorpiovenator bustingorryi

Skorpiovenator, from the late Cretaceous of Argentina. Museo Municipal Ernesto Bachmann

Skorpiovenator bustingorryi. Museo Municipal Ernesto Bachmann

The Abelisauridae represents the best-known carnivorous dinosaur group from Gondwana. Their fossil remains have been recovered in Argentina, Brazil, Morocco, Niger, Libya, Madagascar, India, and France. The group was erected by Jose Bonaparte with the description of Abelisaurus comahuensis. The group exhibits strongly reduced forelimbs and hands, stout hindlimbs, with a proportionally robust and short femur and tibia. The skull of abelisaurids is characterized by having a short and deep cranium at the level of the snout, antorbital fenestra with reduced antorbital fossa, frontals strongly thickened and ornamented conforming well-developed cornual structures, expanded parietal crest with a tall parietal eminence. The nasal bones of abelisaurids are distinctive on having two distinct patterns: Abelisaurus, Carnotaurus, and Majungasaurus have nasals transversely convex and extensively sculptured by highly projected rugosities, while Skorpiovenator and Rugops have nasals posteriorly expanded, with lateral and tall bony crests, which give the nasals a transversally concave profile, and conspicuous foramina over the dorsal surface.

Skull of Skorpiovenator (MMCH-PV 48). (scales bar: 5 cm)

Skull of Skorpiovenator bustingorry (MMCH-PV 48). (scale bar: 5 cm)

Skorpiovenator bustingorry is a derived abelisaurid known from a single and nearly complete skeleton (MMCh-PV 48) recovered from rocks of the famous Huincul Formation (Late Cenomanian–Early Turonian). The skull of Skorpiovenator is strongly ornamented with ridges, furrows and tubercles. Unlike other abelisaurids, in Skorpiovenator both nasals are completely unfused. But the most striking feature is an outstanding series of three large foramina in the skull roof of Skorpiovenator that appear to be an extension of the foramina row from the nasals. This feature likely represent an autapomorphy of Skorpiovenator. CT scans made on the skull of Skorpiovenator and Carnotaurus revealed an internal system of canals linked to the dorsal nasal foramina, which likely represent a correlate for a neurovascular complex. This neurovascular system was probably related to the lateral nasal vessels and perhaps innervated by the trigeminal nerve as in extant archosaurs. The biological significance of such neurovascular system could be linked to a zone of thermal exchange, which may help avoid overheat of encephalic tissues.

References:

Cerroni, M. A., Canale, J. I., Novas, F. E., & Paulina-Carabajal, A. (2020). An exceptional neurovascular system in abelisaurid theropod skull: New evidence from Skorpiovenator bustingorryi. Journal of Anatomy. doi:10.1111/joa.13258

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