Elasmosaur Vertebrae

Elasmosaurs breathed air, were powerful swimmers, and were well-adapted to living in the warm, shallow seas that were common during the Late Cretaceous Period. They had a large shark like tail and a double hinged jaw, like modern day snakes, so they could swallow their prey whole. Species ranged in size from 18 to 55 feet in length, which is a lot of vertebrae if you think about it.

LL Demos & Labs: Fossil Profile: Elasmosaur Vertebrae, Dinosaur Trackways in Texas/Utah