Tusoteuthis longa, an extinct genus of large squid-like cephalopods, inhabited the Western Interior Seaway during the Cretaceous period. Known for its elongated body, it likely reached lengths of up to 11 meters. As a formidable predator, it dominated the marine ecosystem, feeding on fish and other marine creatures.

Tusoteuthis longa is an extinct species of large cephalopod mollusk that lived during the Late Cretaceous period, approximately 94 to 66 million years ago. Fossils of Tusoteuthis longa have been primarily found in the Western Interior Seaway, which covered parts of present-day North America, including regions of modern-day Kansas, South Dakota, and Canada.

The Western Interior Seaway was a vast inland sea that divided North America into two landmasses. During the Cretaceous period, this sea was characterized by warm, shallow marine environments with abundant marine life. The water temperatures were relatively warm, supporting a diverse ecosystem.

Tusoteuthis longa occupied a high trophic level in its marine ecosystem, likely acting as an apex predator. It inhabited open ocean environments within the seaway, preying on smaller marine organisms such as fish and other cephalopods. Its ecological role was similar to that of modern large predatory squid, utilizing its size and speed to capture prey.