Elasmosaurus was about 14 m (46 ft) in length and weighed 2,000 kg (2.2 tons), making it among the largest plesiosaurs. It differs from all other plesiosaurs by having six teeth per premaxilla (the bones at the tip of the snout) and 71 neck (cervical) 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. The neck vertebrae immediately following the skull were long and low, and had longitudinal lateral crests. Like most elasmosaurids, Elasmosaurus had around three pectoral vertebrae. The tail included at least 18 vertebrae.