Turtles and tortoises are believed to have first appeared around 220 million years ago.
Tortoises are cold-blooded, animals with high-domed shells, or carapaces. The only species with a flat shell is the pancake tortoise. Their shells consist of 59 to 61 bones that are covered by plates called scutes. Tortoise shells are made up mostly of keratin, and tortoises are able to sense pain through their shells just as people can sense pain through their fingernails.