Neuroanatomical study of the podocnemidid turtle Neochelys arenarum (Pleurodira), from the early Eocene of France.

Neochelys is an exclusively European Eocene podocnemidid genus belonging to a linage that reached this continent at the early Eocene. The so far available anatomical information about it is relatively abundant, especially considering that of its shell, at least partially preserved for the eight valid species currently considered. By contrast, the skull of very few representatives of the taxon has been identified. Neochelys arenarum is one of the species for which the cranial anatomy is known. It corresponds to the oldest species of this genus, coming from the MP7 zone of the Ypresian (early Eocene) of Southern France. The 3D virtual cranial reconstruction and the detailed neuroanatomical study of a representative of Neochelys are carried out here for the first time based on that species, this being also the first study of this nature performed for a European podocnemidid. In addition, the comparison of the neuroanatomical structures (i.e., the endocranial and labyrinthic cavities, and the nervous and circulatory canals) of N. arenarum with those of other representatives of Podocnemidoidae has been achieved.