Dinosaurs gambol and charge through our imagination as scaly reptilian creatures with menacing teeth, claws, spikes, and hammering, bony bulbs. They roamed Earth roughly 175 million years ago, and most were wiped out by an extinction event roughly 65 million years ago. Thanks to ongoing scientific research, we continue to revise our theories about how dinosaurs evolved, what they ate, and how they moved through their environments. Read about the latest discovery in National Geographic’s Science article: Bizarre Spinosaurus Makes History as First Known Swimming Dinosaur.