Trinacromerum

Trinacromerum's long flippers helped it swim very fast, and scientists think it moved like a 'four-flippered penguin'.1

Its name means 'three tipped femur', which refers to a bone in its hip that had three points.1

Trinacromerum had 46 vertebrae in its spine, including 20 in the neck, 3 in the chest, and 23 in the back.2

Fossils of Trinacromerum have been found in rocks that were once the bottom of a shallow sea that covered central North America.4

It lived from about 106 to 66 million years ago, during the Late Cretaceous period.4

Some scientists once thought Trinacromerum was the same as another plesiosaur called Dolichorhynchops, but now they are considered different.2