Systematic contribution of the auditory region to the knowledge of the oldest European Bovidae (Mammalia, Ruminantia)

The ear region has a strong potential for evolutionary studies. While the petrosal bone suffers from ontogeny and allometry, the bony labyrinth provides crucial information for phylogeny. The study of the bony labyrinth itself allowed for argumentation of the early bovid species Eotragus artenensis and Eotragus clavatus being closely related, while a newly described species and genus of early Bovidae from Montréal-du-Gers (France), formerly attributed to Eotragus, clearly belong to another lineage. The morphology of the bony labyrinth of these oldest bovids confirms that Eotragus is a stem Bovidae, while the new Bovidae is more derived. Since the bony labyrinth is a structure that is little affected by ontogeny, allometry, and sexual dimorphism, we propose this structure and its surrounding petrosal bone as the holotype for this new species. This study shows the importance of the ear region in the context of micro- and macro-evolution.