First neuroanatomical study of the Paleocene bothremydid turtle Taphrosphys (Pleurodira), based on a skull of the Moroccan Taphrosphys ippolitoi, and implications for the marine lifestyle in Taphrosphyini

Abstract Taphrosphyini is a diverse and geographically widely distributed lineage of bothremydid pleurodiran turtles. The first neuroanatomical reconstruction of the Paleogene genus of Taphrosphyini Taphrosphys is presented here, based on the study of a skull of the Moroccan Paleocene species Taphrosphys ippolitoi . Some osseous characters hitherto undocumented for this taxon are recognized in this specimen. Thus, among other anatomical elements, the postorbitals are documented for first time in this taxon, and the columella auris is described for the first time within Taphrosphyini. The use of the CT methodology and the three-dimensional modelling software allowed us to generate the three-dimensional virtual reconstruction of an idealized skull of Taphrosphys ippolitoi . This allows us to recognize several internal cranial structures and compare them with those of the other species of this genus. Most neuroanatomical elements of Taphrosphys ippolitoi are documented here. In addition of characters shared with all other bothremydids, others, shared exclusively with some representatives of this clade, are recognized as evidence for evaluate its lifestyle. The enlarged nasal cavity and the relatively high and wide semicircular canals of the endosseous labyrinth, confirmed here for Taphrosphyini, are convergent with those of other pleurodires identified as marine forms, including the Nigeremydini bothremydids. Thus, these and other anatomical and neuroanatomical traits observed in Taphrosphys ippolitoi are recognized as adaptative responses to marine environments.