Another mass extinction marked the end of the Triassic Period and the beginning of the Jurassic Period. This one was not as severe as the extinction that occurred near the beginning of the Triassic. Throughout the Triassic and Jurassic Periods, the moon orbited a little closer to Earth than it does today. As the Jurassic Period moved forward, the great plant eaters, such as Apatosaurus, Brachiosaurus, and Diplodocus emerged. Named for the Jura Mountains along the border between France and Switzerland, the Jurassic Period was when dinosaurs rose to rule the world. First discovered in 2009, Aardonyx fits into a gap that once existed in the evolution of dinosaurs. As the name suggests, Agilisaurus was agile and had graceful movements. It was also very quick, and it could run away from danger at high speeds using its long hind legs. Allosaurus relied on its excellent hearing and keen sense of smell to locate its prey.