The first Mosasaurus fossil known to science was first discovered in 1764 in a chalk quarry near Maastricht, the Netherlands in the form of a skull, which was initially identified as a whale.Later around 1780, the quarry produced a second skull that caught the particular attention of the physician Johann Leonard Hoffmann, who thought it was a crocodile. He contacted the prominent biologist Petrus Camper, and the skull gained international attention after Camper published a study that identified it as a whale. This caught the attention of French revolutionaries, who looted the fossil following the capture of Maastricht during the French Revolutionary Wars in 1794. In a 1798 narrative of this event by Barthélemy Faujas de Saint-Fond, the skull was allegedly retrieved by twelve grenadiers in exchange for an offer of 600 bottles of wine. This story helped elevate the fossil into cultural fame, but historians agree that the narrative was exaggerated.

After its seizure, the second skull was sent to the National Museum of Natural History, France in 1795 and later cataloged as MNHN AC 9648. The animal, which by then was nicknamed the “great animal of Maastricht,” was found by Camper’s son Adriaan Gilles Camper and Georges Cuvier by 1808 to belong to a marine lizard with affinities to monitor lizards, but otherwise unlike any modern animal. The skull became part of Cuvier’s first speculations about the conception of extinction, which later led to his theory of catastrophism, a precursor to the theory of evolution. At the time, people did not believe that a species could go extinct, and fossils of animals were often interpreted as some form of an extant species.

Cuvier’s idea that there existed an animal unlike any today was revolutionary at the time, and in 1812 he proclaimed, “Above all, the precise determination of the famous animal from Maastricht seems to us as important for the theory of zoological laws, as for the history of the globe.” William Daniel Conybeare coined the genus Mosasaurus in 1822, and Gideon Mantell added the specific epithet hoffmannii in 1829. Cuvier later designated the second skull as the new species’ holotype.