There was a wide variety of species, included lengths from approximately 3 - 18 meters. It has been found on every continent in the world, and even in Sweden and Denmark's upper Cretaceouslayer. The whole family Mosasauridae was extinct in the late Cretaceous period. The first marine reptile of the family "Mosasaur" / Mosasauridae was scientifically discovered in 1778 in Maastricht, Netherlands in a limestone mine by the river Maas. No one knew what was found and a lot of speculations and theories were presented. Not until 1829 was it officially named, it was the genera name Mosasauros (where Mosa stands for Meuse, andsaurus means lizard) and the species name Hoffmanni after fossil hunter and doctor C.K. Hoffman. Limestone layers in Maastricht was by that discovery, and several other so well known, that they have given the nameMaastrichtian to the last part of the Cretaceous period.
The family "mosasaur" / Mosasauridae is classified and is under:
- Animalia / Chordata / Sauropsida / Squamata / Scleroglossa / Anguimorpha
The family is subdivided into several sub-families, genera and species subsequently.