|Average Size||4-17.5 m|
|Average weight||200 kilograms-20 tons|
|Genus||24; see text|
Mosasaurs are a group of extinct lizards that make up the family Mosasauridae. Mosasaurs were typically very large, aquatic predators and appear to be the apex predators of the oceans from the Turonian to Maastrichtian stages of the Late Cretaceous period. The mosasaurs went extinct during the K-Pg extinction event along with plesiosaurs, non-avian dinosaurs and various other forms of life around the world; although relatives, the varanids, are still extant.