Fresnosaurus

Fresnosaurus derscheri was a large plesiosaur from the late Cretaceous of the western interior seaway. Fresnosaurus remains have been found in Los Angeles, California. Fresnosaurus was a small species of plesiosaur probably reaching lengths of about 4 metres long. Fresnosaurus had one predator the Plotosaurus.

In the series...
Fresnosaurus appeared in prehistoric Los Angeles where it was seen swimming and hunting fish when a Plotosaurus killed and ate one.