Résumé
Intraspecific variation of endocranial structures is not widely studied in most mammals, particularly fossil mammals, which are mainly represented by a few preserved crania. However, a description of this variation is necessary to be able to study fossil mammals from an ecological and phylogenetic perspective. To facilitate further analyses on fossil equoids, digital reconstructions of the cranial endocast, petrosal bone, and bony labyrinth were created based on CT scans, taken from a wild population of 12 Equus caballus przewalskii currently being monitored. Using descriptive, biometric, and morphometric analyses, an unsuspected range of intraspecific variation for 40 endocranial characters is revealed. Intraindividual variation can be further understood through the comparison of paired organs from a single individual. These results prompt cautious consideration of these characters, as well as an index for the determination of hearing abilities or encephalization quotients.
Thanks to this work, more is now known about the intraspecific variation of the external morphology of the most frequently studied structures in the endocranium of mammals and more specifically in equoids, where no such study had been undertaken until now. This will help to improve the resolution of fossil endocranial studies.