Crocodiles evolved in a way called punctuated equilibrium, with tandem short- and long-lived species. The same may be true of other “living fossil” species around the world. It’s been 200 million years, but crocodiles haven’t aged a day. You love badass beasts. So do we. Let's nerd out over them together. In a new paper, scientists from the U.K. explain how this notorious “living fossil” has kept its rugged good looks since the heyday of the dinosaurs. In the study, the researchers used “advanced evolutionary modeling” to show why some animals have stayed exactly the same since just after the Triassic-Jurassic mass extinction.