Arthritis, however, may have been less common among dinosaurs than people have assumed, said Rothschild, who treats patients at the Arthitis Center of Northeast Ohio in Youngstown and is a research associate at the Carnegie. Osteoarthritis, for instance, is the type of arthritis that occurs as joint surfaces wear out. It has been assumed that excess weight would increase a person's risk of osteoarthritis. But dinosaur fossils suggest that it's not that simple. Rothschild said it seems the type of joint has more to do with osteoarthritis than weight.
Sauropods have simple hinge joints at the knee that allow the leg only to bend.
Humans, on the other hand, are also able to twist the leg bones. One place sauropods were thought to develop arthritis is in the tail. Many sauropod skeletons have several tail vertebrae fused together. Instead, modern illustrators and skeleton assemblers now show these dinosaurs carrying their tails high off the ground. Both the Apatosaurus and Diplodocus fossil skeletons on display at the Carnegie feature sections of fused vertebrae.