giant sea reptile from the Mezozoic, 1868, from Modern Latin (coined by E.D. Cope), from comb. form of Greek elasmos "metal plate" (from elan "to strike;" see elastic) + -saurus. So called from the caudal laminae and the great plate-bones.
1. Elasmosaurus was not a dinosaur. It was a plesiosaur.
2. Elasmosaurus had a small head. It had sharp teeth and a pointed tail.