Facts About Mosasaurus: Mosasaurus ("Mosa River lizard") is an extinct genus of mosasaurid sauropsid that lived during the Maastrichtian in the Cretaceous period, between 70-66 million years ago in the area of ​​present-day Western Europe, North America, South America and Antarctica. Its name refers to the fact that the first specimen was found near the Meuse River (a European river on the North