Stegosaurus

Stegosaurus was a large, plant-eating dinosaur that lived during the Late Jurassic period, about 155–150 million years ago. It is easily recognized by the two rows of large, bony plates along its back and the four long spikes on its tail, known as the thagomizer, which were likely used for defense. Despite its massive body, Stegosaurus had a very small head and brain, roughly the size of a walnut, and primarily fed on low-lying plants like ferns and cycads.

Stegosaurus could grow up to 30 feet long and weigh around 5 tons. Fossils have been found in western North America, particularly in Colorado, Wyoming, and Utah.