The shoulders and hips are also incorporated into the shell. The outside of the shell is covered by modified scales, scutes . The desert tortoise first appeared in the fossil record over 40 million years ago and has since adapted to the habitats of the southwestern United States. Its ranges include southern Nevada, southern California, southwestern Utah, northern and western Arizona, and northern Mexico. Tortoises live on land and do not swim.
Turtles are swimmers.
Tortoises also have domed shells while the shells of turtles are usually flat. Tortoises also have thick, heavy scales on their front legs and use their legs to cover their faces when in danger. Turtles do not shield their faces. Tortoises only have 4 toes on their back feet and turtles have 5. Tortoise success depends upon the ability to find food, shelter and to reproduce.