This document provides information about several different dinosaurs. It states that dinosaurs lived millions of years ago during the Jurassic and Cretaceous periods. Tyrannosaurus rex, which lived 66 million years ago during the Late Cretaceous, was a carnivorous theropod that grew up to 13 meters long and weighed 7 tons as an adult. Stegosaurus, from the Late Jurassic period 150 million years ago, had sharp spikes on its back and was about the size of a school bus. Apatosaurus had a very long neck and tail and is thought to have had one of the longest bodies of all dinosaurs.