Mosasaurus is an extinct genus of large marine reptiles known as mosasaurs. These reptiles lived during the Late Cretaceous period, approximately 66 to 70 million years ago. Mosasaurs were not dinosaurs but belonged to a group of reptiles called squamates, which includes lizards and snakes.

Mosasaurus was a formidable predator in the oceans of the Late Cretaceous. It had a streamlined body, a powerful tail, and flippers adapted for swimming. With a length reaching up to 18 meters (59 feet), Mosasaurus was one of the largest known mosasaurs. Its body shape and limb modifications suggest it was a fast and agile swimmer, enabling it to pursue and capture its prey.

Like modern marine predators, Mosasaurus had a varied diet. Fossil evidence indicates that it primarily fed on fish, although it also consumed other marine animals such as turtles, squid, and ammonites. Its sharp, conical teeth were well-suited for grasping and tearing apart its prey.

Fossils of Mosasaurus have been found in various locations around the world, including North America, Europe, and Africa. These fossils have provided valuable insights into the biology, evolution, and paleoecology of mosasaurs. Through careful examination of these remains, scientists have been able to reconstruct the anatomy and understand the evolutionary relationships of Mosasaurus within the broader context of marine reptiles.