1. In mosasaurs, these features may be internal adaptations to fully marine lifestyles.

2. Mosasaur bones have also been found with shark teeth embedded in them.

3. Despite the many mosasaur remains collected worldwide, knowledge of the nature of their skin coverings remains in its early stages.

4. For example, it is thought that ammonites were the principal food of mosasaurs, a group of giant marine reptiles that became extinct at the boundary.

5. A skeleton of Tylosaurus proriger from South Dakota included remains of the diving seabird Hesperornis, a marine bony fish, a possible shark, and another, smaller mosasaur (Clidastes).

6. Mosasaurs were so well adapted to this environment that they gave birth to live young, rather than returning to the shore to lay eggs as sea turtles do.