The Late Cretaceous was an era in evolutionary history, preceeded by the Jurassic, Triassic and Permian periods. The Cretaceous period was the heyday of the dinosaur evolution. Huge carnivores like Tyrannosaurus rex and Ceratosaurus appeared, as did Triceratops and many, many others. There was a tremendous diversity in dinosaur species. Mammals were flourishing, and flowering plants developed and radically changed the landscape. The breakup of the supercontinent Pangaea into separate continents was underway. The separation of Laurasia and Gondwana was complete. In the first half of the Cretaceous, temperatures were warm, seasonality was low, and global sea levels were high (no polar ice!). At the end of the Cretaceous, there were severe climate changes, lowered sea levels, and high volcanic activity .The Cretaceous period ended 65 million years ago with the extinction of the dinosaurs and many, many other prehistoric life forms. This mass extinction was the second-most extensive in the history of the Earth.