A new specimen of Cardiocorax mukulu with a nearly complete cranium from Angola

Abstract

We report a plesiosaur specimen that includes the most well complete skull of an Elasmoaurid plesiosaurian from Sub-Saharan Africa. The new specimen, MGUAN PA278 from the Maastrichtian outcrops of Bentiaba, Angola includes fully preserved semicircular canals, both hyoids, a nearly complete mandible, seventeen cervical vertebrae, a rib and rib fragment, a propodial, and paddle elements. A CT scan of the cranium was performed at UTCT in Austin, TX to visualize all aspects of the cranium and to produce a digital model of the skull and casts of the endosseous labyrinths. The cranium was segmented at SMU using AMIRA software and compared to other well preserved elasmosaurid plesiosaurian skulls from collection visits and from the literature. MGUAN PA278 is diagnosed as Cardiocorax mukulu based on the morphology of the middle cervical neural spines. C. mukulu is returned from a phylogenetic analysis as a basal elasmosaurid outside of the Elasmosaurinae-Aristonectinae clade and the sister taxon of Libonectes morgani. The compact morphology of the endosseous labyrinth in MGUAN PA278 may be an adaptation to living in a pelagic environment.