Comparative morphology of the dormouse skull

Abstract

Dormice exhibit both inter- and intrageneric variation in cranial and mandibular morphology. Using geometric morphometrics, the form of eight out of nine extant dormouse genera was analysed, to provide a better understanding of the overall morphological variation present within Gliridae. Three genera representing the subfamilies, were studied in more detail. Species-, genus- and family-specific morphological trends are linked with certain habitats and feeding strategies. Smaller dormice show adaptations to a more arboreal lifestyle such as a relatively enlarged braincase and an inferiorly reoriented foramen magnum. Larger dormice show cranial modifications, including clear flattening of the skull and a more posteriorly positioned foramen magnum, hinting towards a more rupicolous lifestyle. Furthermore, specimens inhabiting arid areas appear to have more inflated auditory bullae, whereas other variable features, such as the length of the incisive foramen, were not associated with either size changes nor climatic variables. Lastly, more robust and horizontally orientated zygomatic arches as well as increased robusticity of the molar row appear to be linked with herbivory in dormice, whereas thinner arches and small concave molars are seen in more insectivorous species. This study results in a better understanding of ecological drivers underpinning the morphological divergence present within Gliridae.