Mosasaur
Mosasaurs (from Latin "Mosa" meaning the 'Meuse river', and Greek σαύρος "sauros" meaning 'lizard') are an extinct group of large marine reptiles containing 38 genera in total. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. Mosasaurs probably evolved from an extinct group of aquatic lizards known as aigialosaurs in the Early 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.
Paleontology in New Mexico
In 1947, an American Museum field party led by Edwin Harris Colbert discovered a bonebed including the skeletons of more than 1,000 "Coelophysis" at Ghost Ranch. Later, in 1953 University of New Mexico graduate student William Chenoweth discovered three important sites where dinosaurs were preserved in Morrison Formation rocks. He found a fragmentary "Allosaurus", sauropods, and "Stegosaurus". Three years later, in 1956, mastodon teeth were discovered by a nine-year-old boy who was out hunting for Indian arrowheads. These well preserved teeth are now curated by the University of New Mexico Museum. During the 1960s, uranium prospector Rodney Peterson discovered a new fossil site west of Albuquerque. Actual paleontological excavation at the site would be several decades away, however.