A digital redescription of the Middle Miocene (Langhian) carettochelyid turtle Allaeochelys libyca

Abstract

Allaeochelys libyca is a carettochelyid turtle from the Middle Miocene of Libya. The species is the only valid carettochelyid taxon recovered from Africa and was named based on fragmentary material that includes a partial cranium and isolated shell remains. The description of the holotype cranium was limited to external aspects, and micro-computed tomography was only performed later on that material. Here, we use these micro-computed tomography scans to reinvestigate the external and internal anatomy of the holotype cranium to document several erroneous anatomical interpretations and provide new insights into the morphology of the trigeminal foramen area, the endosseous labyrinth, and circulatory system of Allaeochelys libyca. The anatomical insights provided herein have the potential to be translated into new phylogenetic characters that are expected to improve the resolution among the Anosteira and Allaeochelys lineages, which are still poorly resolved.