Stegosaurus means "covered lizard" in Greek. This dinosaur had a double row of protective plates covering its back and tail. In addition to acting as a protective covering, these plates may have operated as a sort of cooling device -- wind flowing between the plates would have helped lower the body temperature of a Stegosaurus on hot days. The Stegosaurus is known to have grown as tall as 12 meters (40 feet) and weighed as much as 5 tons.