Thalassomedon haningtoni, a long-necked plesiosaur, thrived in the Late Cretaceous seas. Known for its impressive 40-foot length and elongated neck, it was an adept predator. Its paddle-like limbs enabled swift swimming, while its sharp teeth were perfect for catching fish and squid, integral to its marine ecosystem.

Thalassomedon haningtoni was a genus of plesiosaur that lived during the Late Cretaceous period, primarily found in what is now known as North America. Fossils have been discovered in regions that are part of present-day Colorado, Wyoming, and Kansas, which were once submerged under the Western Interior Seaway.

During the Late Cretaceous, the Western Interior Seaway provided a warm, shallow marine environment with abundant marine life. The climate was generally warm and stable, supporting a diverse range of marine species, including various fish, cephalopods, and other marine reptiles.

Thalassomedon haningtoni occupied a niche as a large marine predator. It likely hunted fish and smaller marine reptiles, using its long neck to effectively catch prey. This adaptation allowed it to exploit a range of prey types in the open ocean environment of the Western Interior Seaway.