Mosasauridae is a family of large, marine reptiles that lived during the late Cretaceous period, approximately 70 to 66 million years ago. These creatures were characterized by their elongated bodies, powerful tails, and paddle-like limbs, which made them efficient swimmers. They were apex predators, feeding on fish, squid, and other marine animals. Mosasaurids are closely related to modern lizards and snakes, sharing a common ancestor. Fossils of these reptiles have been found on every continent, indicating their widespread distribution in ancient oceans. Their extinction coincided with the mass extinction event that also wiped out the dinosaurs.