Phosphorosaurus

Phosphorosaurus ("phosphate lizard") is an extinct genus of marine lizard belonging to the mosasaur family. Phosphorosaurus is classified within the Halisaurinae subfamily alongside the genera Pluridens, Eonatator, and Halisaurus.

Stratigraphically, Phosphorosaurus is only known from the Maastrichtian age of the Late Cretaceous. Although treated as synonymous with Halisaurus in the past, recent studies recognize it as a valid genus. Two species are known: Phosphorosaurus ortliebi, from the Craie de Ciply Formation in Belgium, and P. ponpetelegans, from the Hakobuchi Formation of Hokkaido in Japan. P. ponpetelegans is only known from the very earliest Maastrichtian, whilst P. ortliebi lived throughout the Maastrichtian.