Tylosaurus proriger was a large marine reptile, part of the mosasaur family, that lived during the Late Cretaceous period. It had a streamlined, elongated body, with a powerful tail and robust jaws filled with sharp teeth. This apex predator inhabited ancient shallow seas, preying on fish, sharks, and even other marine reptiles.

Tylosaurus proriger was a species of mosasaur that lived during the Late Cretaceous period, approximately 85 to 80 million years ago. Fossil evidence indicates that its native region was primarily within the Western Interior Seaway, a vast inland sea that divided North America into two landmasses. This seaway covered parts of present-day central United States and Canada, including areas of Kansas, South Dakota, and Manitoba.

The Western Interior Seaway provided a marine environment with warm, shallow waters that were rich in marine life. This habitat was characterized by a subtropical to temperate climate, with abundant marine prey such as fish, ammonites, and other marine reptiles.

Tylosaurus proriger occupied a top predatory niche within its marine ecosystem. As a large marine reptile, it was well-adapted to hunting in open waters. Its streamlined body and powerful jaws made it an efficient predator, capable of capturing a variety of marine animals. This ecological niche was supported by the diverse marine biodiversity present in the seaway, allowing Tylosaurus to thrive as one of the dominant predators of its time.