Mososaurus XL tooth found in Morocco.

Mosasaurus, also called mashed lizard, is a genus of the Mosasauridae family, a group of extinct saurians who lived in the sea. The first fossil remains were found at Maastricht in Sint-Pietersberg, which lies on the bank of the river Maas (Latin: Mosa), and Mosasaurus is named after the river. The species from the genus lived in Maastrichtien, the last part of the Cretaceous period, 71.3 to 65.4 million years ago. It took until 1822 before a publication appeared in which the "head of Godding" received a scientific name. Until then, the fossil was usually referred to in French with "le grand animal de Maëstricht" ("the great animal of Maastricht"). In 1822, William Conybeare published the name Mosasaurus as a generic name for the fossil, after the Latin word for "Maas": Mosa and the Greek word for "lizard": sauros; the holotype was MNHNP AC 9648, the Parisian skull. [33] In 1829 Gideon Mantell published the generic name as Mosasaurus hoffmannii, honoring Hoffmann as the alleged discoverer of the fossil. The name was published by Mantell as Mosasaurus hoffmannii, and despite the many publications in which the epithet is spelled as a hoffmanni, the name ending with double "i" is the correct spelling. In the 19th century it was customary to place each mosasaur in the genus Mosasaur and to name almost every find as a separate species; thus a multitude of species names arose. In retrospect, most names turned out not to be valid and to be considered as synonymous or to be placed in a different gender. This process seems to lead in recent years to the situation where Mosasaurus hoffmannii remains with only a few other species in the genus.