<human>:  When did the dinosaur called ‘stegosaurus’ live?
<bot>: The stegosaurus lived about 150 million years ago. It was a herbivore that lived in the Jurassic period. It was a very large animal, about 20 feet long and weighing about 6 tons. It had a long neck and a long tail. It had a long, sharp beak for eating plants.