We study the Late Jurassic (Tithonian) turtle Uluops uluops using micro-computed tomography
scans to investigate the cranial anatomy of paracryptodires, and provide new insights
into the evolution of the internal carotid artery and facial nerve systems, as well
as the phylogenetic relationships of this group. We demonstrate the presence of a
canalis caroticus lateralis in Uluops uluops, the only pleurosternid for which a palatine
artery canal can be confidently identified. Our phylogenetic analysis retrieves Uluops
uluops as the earliest branching pleurosternid, Helochelydridae within Pleurosternidae,
and Compsemydidae including Kallokibotion bajazidi within Baenidae, which suggests
at least two independent losses of the palatine artery within paracryptodires. We
expect future studies will provide additional insights into the evolution of the circulation
system of paracryptodires, as well as clarifying relationships along the turtle stem.