Elasmosaurus

Elasmosaurus is a plesiosaur from the Late Cretaceous. However, they are mistakenly depicted to be in the Middle Jurassic.

One was seen swimming with a school of Leedsichthys before it was seen with other Elasmosaurs swallowing gastroliths to digest their food inside their stomachs. However, the same male Liopleurodon that lost an eye during mating a female goes after one of the young Elasmosaurus. The Elasmosaurus once again swims into the Leedsichthys school and one of the Leedsichthys accidentally hits the Liopleurodon in the face which killed him, saving the Elasmosaurus.

Trivia

 * A good (and an actual Jurassic one) plesiosaur that would replace Elasmosaurus in the Jurassic would be Cryptoclidus.


 * A book called Jurassic Shark shows Elasmosaurus who is also mistakenly depicted in the Jurassic.