Unidentified ichthyosaur

The Unidentified ichthyosaur was a species of ichthyosaur that only appeared in storyboards cut from the film.

Identity
One identification proposed by fans is Ichthyosaurus. However, no Ichthyosaurus had a sail on its back like the one in the storyboard. Another identification is Mixosaurus. However, the animal on the storyboard is both larger than the real animal and has a sail on its back, a feature the real animal did not have.