This skull from a huge swimming lizard was found in the lower Fox Hills formation along the Moreau River. It is not a dinosaur but rather a distant relative to the Komodo Dragon of Indonesia.

This specimen found by Mrs. Ross is about 66 million years old, about 5 million years younger than any previously known skull.

Older Pierre shale deposits from the upper cretaceous of the Dakotas have produced fossil remains of several genera of Mosasaur, including Clidastis, Tylosaurus, and Platecapus.

The exact species and genera of this specimen is yet to be determined.

Mosasaurs lived along the shores of oceans where they fed on fish, birds and maybe even ammonites. They had a double hinged jaw which allowed them to swallow prey bigger than their own head.

Mosasaurs may have crawled onto land to lay their eggs or as recent fossils suggest they may have given live birth to their young in the water.

A complete skeleton of the very large Mosasaurus Condon is on display at the Museum of Geology in Rapid City.

Donated by the Ross family

Prepared by Steve Haire