What is a Placochelys dinosaur?

Answer 1

Acutally, Placochelys was a placodont, not a dinosaur. Placodonts are a group of strange, aquatic repiles that resemble many modern reptiles but aren't related to them or to dinosaurs. A Placochelys looked like a sea turtle, but with huge buck teeth for crushing the shells of aquatic creatures and big bony armor plates on its back (like ankylosaurus). This armor protected it from the few other predators of the time, but made it a slow swimmer; it needed to live in shallow water close to shore so it didn't drown. Placochelys lived in the Late Triassic, when the first dinosaurs had just evolved and the land was ruled by the early crocodiles and their relatives. The slow and heavy placodonts were being replaced by swifter aquatic reptiles like the plesiosaurs and ichthyosaurs. The Triassic Period ended with a fairly large extinction event that killed off many groups of animals including the placodonts.