Mosasaur

Mosasaurs were large marine reptiles that were well-adapted to living in the warm, shallow, epicontinental seas prevalent during the late Cretaceous Period, between 145.5 and 65.5 million years ago. They breathed air & were powerful swimmers making them so well adapted to this environment that they gave birth to live young, rather than return to the shore to lay eggs, as sea turtles do. Mosasaurs had many qualities of a modern day snake, they had two rows of teeth in their upper jaw, the main set, and a smaller set toward the rear & center of their mouths.