Neuroanatomy and auditory adaptations of Sidersaura marae: Insights into the palaeoecology of rebbachisaurid sauropods

Abstract

The neuroanatomy of rebbachisaurid sauropods is known from the Gondwanan taxa Nigersaurus taqueti, Campananeyen fragilissimus, and Limaysaurus tessonei. Here, the endocranial morphology of the recently named rebbachisaurid Sidersaura marae is reconstructed and analyzed. A large portion of the endocast could be visualized, inclusive of the cranial nerves V to XII from the right side, the major associated vasculature, and the labyrinth of both inner ears. Its morphology differs from that of other Rebbachisauridae, particularly in the rostral dorsal expansion that is not entirely covered by the skull roof (existence of a frontoparietal fenestra). The presence of traces of dorsal diploic vessels, and the particular pathway of cranial nerve XI?/XII(rostral branch)? further set the endocast apart from those of other rebbachisaurids. The new data from Sidersaura suggest that the presence of a rostroventrally inclined transversotrigeminal vein and the basilar artery piercing the dorsum sellae are neuroanatomical features characteristic of Rebbachisauridae. Finally, rebbachisaurids may stand out from other sauropods in the variation in hearing capabilities relative to body size, suggesting potential palaeoecological selective pressures on the auditory sensitivity and plausible communication faculties.