Stegosaurus were herbivorous, four-legged, armored dinosaurs characterized by the distinctive kite-shaped upright plates along their backs and spikes on their tails. Weighing 5 tons, and 30 feet long, they had a small head and brain only the size of a walnut and weighing just 3 oz. They are one of the better-known dinosaurs that have been featured in film, postal stamps, and in many other types of media.