8Dinosaurs once ruled the Earth--and they still rule the record books, because they had to be extreme to survive in prehistoric days So meet the creatures that have never been equaled, including Amphicoelias, who outsized all the other dinos, and Spinosaurus, the biggest two-legged predator ever. In addition, there's a timeline, a comparison of each dinosaur's size to a human's, and fun facts and figures.