Braincase anatomy and palaeoneurology of Venetoraptor gassenae , a lagerpetid pterosauromorph from the Late Triassic of southern Brazil

Abstract

There is a growing consensus that pterosaursand the flightless Lagerpetidae are closely related. This relationshipis supported by apomorphies throughout the skeleton,including endocranial character states such as awell-developed floccular fossa and a tall anterior semicircularcanal. Our knowledge of lagerpetid anatomy has beenimproved by recent discoveries. Among them, the Brazilianrecord plays a significant role, having produced twodescribed species, Ixalerpeton polesinensis and Venetoraptorgassenae, and several more fragmentary specimens. In thisstudy, we used an x-ray micro-computed tomographic scanto describe the endocranial anatomy of the holotype of Venetoraptorgassenae. The endocranial anatomy of Venetoraptorgassenae is similar in shape to that of other described lagerpetids,and we reach the following conclusions: (1) in pterosaurs,the metotic foramen exits posteriorly, whereas inlagerpetids and dinosauromorphs it exits through the lateralwall of the braincase; and (2) Venetoraptor gassenae is uniqueamong lagerpetids in having only one exit for cranial nerveXII, expanding its differential diagnosis. These differenceshighlight that the braincase anatomy of lagerpetids is alignedwith the anatomical disparity observed in the group. Finally,we discuss why future studies should focus on comprehendingpatterns of braincase pneumaticity in avemetatarsalians.