Description:  Tyrannosaurus rex had sharp teeth that could bit through bone, and Triceratops must have been an intimidating sight with their large frills and prominent horns. It's no wonder dinos ruled Earth back in the Cretaceous period. But what about creatures flying high in the sky or predators lurking under the waves? Many of these animals were not dinos. Become a paleontologist of the Cretaceous as you explore colorful illustrations and fabulous fossil photos to take a trip back in time and discover who was and was not a dino.