NEW SPECIMENS OF ANGOLASAURUS BOCAGEI AND COMMENTS ON THE EARLY RADIATIONS OF PLIOPLATECARPINE MOSASAURS POLCYN, Michael, SMU, Dallas, TX, USA; JACOBS, Louis, SMU, Dallas, TX, USA; MATEUS, Octávio, Museu da Lourinhã, Lourinhã, Portugal; SCHULP, Anne, Natuurhistorisch Museum Maastricht, Maastricht, Netherlands New, well preserved material of the Turonian mosasaur Angolasaurus bocagei from the Tadi Beds of the Itombe Formation in northern Angola, allows detailed redescription of its morphology and reassessment of its phylogenetic relationships. Angolasaurus had been previously referred to the genus Platecarpus; however, phylogenetic analysis confirms the valid taxonomic status of A. bocagei, and reconstructs that taxon within a clade that also includes the genera Selmasaurus and Ectenosaurus. These forms are united by an elaborated infrastapedial process of the quadrate and a unique ridge-like descending process of the parietal forming the supraoccipital articulation, but also retain a relatively plesiomorphic configuration of the braincase. That clade is united with all other plioplatecarpines by a number of derived characters including the presence of a novel basicranial circulation pattern. In Africa, North and South America, early plioplatecarpines are known by the Middle Turonian and Angolasaurus and closely related forms appear by the Upper Turonian. Selmasaurus and Ectenosaurus are a rare faunal component of the Santonian and Campanian of North America. Platecarpus planifrons appears in the Coniacian of North America and represents the plesiomorphic condition of the clade containing the remaining species of Platecarpus and Plioplatecarpus, that appears in the Santonian and persist until the end of the Cretaceous, reaching global distribution. The temporal and geographic distribution of these radiations suggest influence of paleogeography and eustatic sea levels.
|Journal||Journal of Vertebrate Paleontology|
|Publication status||Published - 1 Jan 2009|