Placodus was a genus of marine reptiles, belonging to the order Placodontia, which swam in the shallow seas of the middle Triassic period ( 240 million years ago ). Fossils have been found in Central Europe and China. The animal reached a total length of up to 2 meters (6.6 ft). They were specialized for a durophagous diet of shellfish,molluscs, brachiopods, crustaceans. Placodus was slow and clumsy out of water.