One of the most famous of all the dinosaurs, Stegosaurus lived around 150 million years ago. Because of its tiny head and brain, many consider Stegosaurus and other plated dinosaurs to have been the least intelligent of all the dinosaurs.
Stegosaurus was the largest of the Stegosauridae, or plated dinosaurs. It was just a little larger than a modern day elephant, and had a line of bony plates running down its backs. These plates were hollow and soft. For this reason, they were probably not used as protection. If not for protection, then why did Stegosaurus have plates?
Scientists believe that the hollow plates were used to help the animal regulate or control its temperature. Blood could flow into the bony plates, and either cool down or heat up. This is one way that such a large cold-blooded animal could survive.
The end of Stegosaurus' tail had four long sharp spikes that were no doubt used to protect itself against large meat-eaters.