Elasmosaurus

Elasmosaurus ('thin plate') is a genus of plesiosaur with an extremely long neck that lived in the Late Cretaceous period, 80.5 million years ago.

Description
Elasmosaurus was about 14 m (46 ft) in length and weighed 2,000 kg, making it among the largest plesiosaurs. It differs from all other plesiosaurs by having six teeth per premaxilla and 71 neck vertebrae. The skull was relatively flat, with a number of long pointed teeth. The lower jaws were joined at the tip to a point between the fourth and fifth teeth.