Turtles have been around for a long time they even been around when there were dinosaurs. They were way different than the turtles we have today like the one above. One prehistoric turtle is Carbonemys cofrinii, (coal turtle) it is the size of a small car and it's head is the size of a football. The picture is below if you want to check it out to see how big it is.
The Henodus this Triassic placodont looked really like a modern turtle.