Fossilized Plesiosaur tooth embedded in the fin bone of an ichthyosaur found in the Bristol Channel from the Hettangian stage of the early Jurassic, dating 200 million years ago. The ball of bone overgrowth around the tooth shows that the wound has healed. The groove on the surface of the bone is a scar left by a tooth that has slipped on the bone. Ichthyosaurs were a type of extinct giant marine reptile, that were widespread during much of the Mesozoic (252-66 million years ago) era. Collection Jean-Philippe et Francois-Xavier Blouet, paleontologists.