Turtles are a group of reptiles, well known for their shell that covers most of their bodies. They are designated in the order of "Testudines" in the reptile group. The ancestors of turtles are believed to originate from back in the Mesozoic era, nearly 200 million years ago. Exactly what they used to look like when they came into this earth is often disputed. Some scientist state that the turtles are the only surviving breed of the anapsida clade. Others say that they surfaced with anapsida traits, long after the ancient clade was extinct. As of today there are 300 species of turtles, some highly endangered.