An extinct seasnake-like Mosasaur in the Niobrara sea, North America, late Cretaceous. A pterosaur, Pteranodon, at left, and sea turtle at right. Mosasaurs were probably giant sea monitor lizards of their time. Illustration from Wilhelm Bolsches Das Leben der Urwelt, Prehistoric Life, Georg Dollheimer, Leipzig, 1932.
An extinct seasnake-like Mosasaur in the Niobrara sea, North America, late Cretaceous. A pterosaur, Pteranodon, at left, and sea turtle at right. Mosasaurs were probably giant sea monitor lizards of their time. Illustration from Wilhelm Bolsches Das Leben der Urwelt, Prehistoric Life, Georg Dollheimer, Leipzig, 1932.