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Cryptoclidus was an 26 foot, eight ton member of a plesiosaur genus from the Middle Jurassic period (180-145 MYA) English deposits.

Creature attributes

Physical appearance and biology

At 4[1]-8 meters in length[2] (13[1]-26ft[2]) with a neck 2 meters long[1] and weighting 8 tonns,[2][3] Cryptoclidus was unlike other plesiosaurs because it had a seal-like body plan. This body-type allowed it to haul itself onto land, though they were rather cumbersome on land than in water.[3]


Cryptoclidus had a skin color that was blend of brown and dark gray with black spots and had a white underbelly.

Behaviour and traits

Cryptoclidus would come onto land for various reasons. These reasons include to bask in the sun before returning to the water, to rest for the night,[2][3] evade predators, and probably even to breed.

[1] Cryptoclidus would hunt anchovy-sized fish,[1] squid,[1][2] and ammonites,[1] such as Perisphinctes.[2] Because of their body size[1], they were ambush predators,[1][2] though they could have searched soft seabead sediments for crabs, worms, and fish.[1] They were prey for the larger Liopleurodon.

[3] [2][1]

In Walking with... Series

A pod of Cryptoclidus on the bank of the shore.

Walking with Dinosaurs

Cruel Sea

Cryptoclidus was featured in the third episode of WWD. It was a stand-in for Plesiosaurus as a plesiosaur. It lived in a small colony, hunted fish underwater and came ashore at night to escape Liopleurodon.


Behind the Scenes

  • Cryptoclidus couldn't go on land.
  • Long neck Plesiosaurs like Cryptoclidus and short neck Pliosaurs like Liopleurodon are now thought to have flukes on their tails, and not smooth lizard-like tails.
  • Cryptoclidus lived from 166 to 164 million years ago so it would not have been alive 149 million years ago.
  • In Walking With Dinosaurs Short Bites, they were known as Plesiosaurs.

List of appearances

Notes and references