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Derived members of the enigmatic mammalian order Desmostylia have molars comprising appressed columns whose morphology does not render their function in feeding simple to discern. Here we describe a new genus and species,Ounalashkastylus tomidai, more derived thanCornwalliusbut less derived thanDesmostylusandVanderhoofius, which develop a hypertrophied medial eminence on the dentary ontogenetically. Tooth morphology, vaulted palate and the medial eminence, which can rise to the level of the occlusal surface of M2, suggest that derived desmostylids clenched their teeth strongly while employing suction during feeding, most likely on marine and coastal plants. [ABSTRACT FROM PUBLISHER]

New mosasaur fossils from Maastrichtian beds at Bentiaba, Angola, representing elements of the skull and postcranial axial skeleton from two individuals of the durophagous genus Globidens, are reported. Based on dental morphology, specifically the inflated posterior surface and vertical sulci, the Bentiaba specimens are identified as Globidens phosphaticus, a species defined by characters of a composite dentition from the Maastrichtian of Morocco. Comparisons indicate that G. phosphaticus is most closely related to G. schurmanni, from the late Campanian of South Dakota, the youngest north American Globidens species at about 72.5 Ma. The morphology of the premaxilla and its relationship with the maxillae is unique among mosasaurs, and supports the taxonomic validity of G. phosphaticus. In contrast with earlier species of the genus, G. phosphaticus is currently known from north and west Africa, the Middle East and the central eastern margin of South America, suggesting it may have been restricted to the Maastrichtian tropical zone as previously hypothesised. [ABSTRACT FROM AUTHOR]