Ichthyosaurs

These were dolphin-like marine reptiles. Just as dolphins breathe air and were evolved from land mammals, the ichthyosaurs could not breathe underwater, and their ancestors were land reptiles.

We know that Gloucestershire must have been near the coast. This is because among the fossil sea creatures are land plants and animals that were washed out to sea with the tide. The surviving fossils tell us that these seas must have been warm and full of life. We have many kinds and sizes of extinct fish, rays, molluscs, and crustaceans, as well as the sharks and carnivorous reptiles that fed upon them.