Mosasaurus is a genus of large, aquatic reptiles that lived during the Late Cretaceous period, approximately 70-66 million years ago. These creatures were marine predators, resembling giant, carnivorous lizards, and are often considered one of the apex predators of their time. Mosasaurus had a streamlined body with powerful jaws filled with sharp teeth, enabling it to hunt a variety of prey including fish, ammonites, and even other marine reptiles. Fossil remains of Mosasaurus have been found in North America, Europe, and Africa, providing valuable insights into the ancient marine ecosystems of the Cretaceous period.