Stegosaurus was a herbivore from the Jurassic. It may have eaten a variety of green plants including ferns, horsetails, and conifers. Some scientists believed that the 17 plates on its back allows it to cool down on hot days and warm up on cold days. It used its spiky tail as a weapon to deter large predators from eating them, similar to Kentrosaurus. Scientists also believe that they had a second brain in the back end of there body so, they do not intend to swing the tail on purpose unless it is against a predator like an Allosaurus. It lived in North America during the Jurassic Period. The most notable member is Morris.