In Arizona’s Petrified Forest National Park, researchers are scouring the fossil-rich surface and drilling deep into ancient rocks to learn more about what happened during the late Triassic, some 201 million to 235 million years ago. It was a time when the world underwent repeated climate shifts and catastrophic mass extinctions, and both early dinosaurs and mammals evolved. What the researchers learn here may not only allow them to write a precise chronology of the period, but shed light on wider questions including how climate swings work, and how they affect ecosystems. READ THE FULL SCIENTIFIC STORY