Fossil skull of Mosasaurus, a genus of the Mosasauridae family, now extinct aquatic reptiles of the order of the squamates. These carnivores roamed shallow and coastal seas during the Maastrichtian age of the late Cretaceous period, between about 70 and 66 million years ago. In Western Europe, North America, and possibly Japan and New Zealand. The skull seen here was extracted from the Cretaceous marlstone beds and has a length of about 75 cm.