Cretaceous Period, 145-65 million years B.P. A jaw section displaying two teeth from the Mosasaur Prognathodon sp.; held in a card collector's tray. 108 grams, 93 mm (3 5/8 in.). From Morocco, North Africa. From a Cambridgeshire, UK, collection. The Mosasaur is an extinct, large marine reptile dinosaur with a snake-like body, long snout and paddle-like limbs. Found worldwide, they competed with other well-known sea predators of the Late Cretaceous, such as plesiosaurs and ichthyosaurs, for food, existing primarily on a diet of ammonoids, cuttlefish and fish. [No Reserve]