View All Photos

Mosasaur Fossil

Mosasauridae (family), “Mosasaur Family”

Sensitive Classification

Fossils are sensitive in nature and should not be collected unless it is done legally and responsibly. Vertebrate fossils are illegal to collect on public lands.

On the Web

On Wikipedia

Mosasaurs (from Latin Mosa meaning the 'Meuse', and Greek σαύρος sauros meaning 'lizard') comprise a group of extinct, large marine reptiles containing 40 genera in total. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. They belong to the order Squamata, which includes lizards and snakes. Mosasaurs probably evolved from an extinct group of aquatic lizards known as aigialosaurs in the Earliest Late Cretaceous. During the last 20 million years of the Cretaceous period (Turonian–Maastrichtian ages), with the extinction of the ichthyosaurs and pliosaurs, mosasaurs became the dominant marine predators. They became extinct as a result of the K-Pg event at the end of the Cretaceous period, about 66 million years ago.