Great Dinosaurs Stegosaurus The Stegosaurus was a large, armored. plant-eating dinosaur that lived during the Upper Jurassic Period in North America. An adult would weigh over 4.5 Tons, but inside its unusually small head, its brain would weigh less than three ounces. The Stegosaurus was a very successful dinosaur, so its small brain did not appear to affect it too much. The Stegosaurus has extremely short front limbs that gives it a very rounded back and places its small head very close to the ground. Because of this, it is thought that it would have been restricted to feeding at or near ground level. Stegosaurus has two sets of long bony spikes on the tail that probably functioned in defense against predators, and a double row of plates along its back. The hand painted Stegosaurus measures 12.25" L x 6.5" H (28.5 x 16.5 cm). Product includes a five-language educational hang tag. Made of hard plastic. Very durable, great for outside play.