A predacessor to the legendary Mosasaurus, the Cymbospondylus is the largest carnivore during it's time. It appears during Dangerous Seas.
The Cymbospondylus resembles dolphins and sharks due to their flippers arrangement. They were quite slow for their size and was quite prone to gliding. It's teeth were fragile when compared to other marine reptiles.
During Dangerous Seas it eats the Tanystropheus tail and tries to attack Nigel only for it to leave.