Trinacromerumis an extinct genus of sauropterygian reptile, belonging to the polycotylid family of plesiosaurs. This marine reptile grew to about 3 meters (9.8 feet) in length and is thought to have preyed on small fish, as indicated by the shape of its teeth. Its long, powerful flippers allowed it to reach high swimming speeds. The creature's overall appearance has been likened by Richard Ellis to a "four-flippered penguin." The name Trinacromerum translates to "three-tipped femur," referring to a distinct feature of its skeletal structure. Fossils of this species have been found in Late Cretaceous deposits, primarily in areas that are now part of modern-day Kansas and Manitoba.

Locality: Kansas
Formation: Pierre Shale
Length: 1m (41”)

Skull: $3,900