Before dinosaurs ruled Earth, something wiped out roughly 60% of all life on the planet. Past research showed that this extinction corresponded with a release of carbon dioxide into the atmosphere, possibly from a massive volcanic area, but researchers have struggled to pinpoint when eruptions occurred. A new study confirms there was volcanic activity at the same time as the extinction about 200 million years ago.

How they did it: Eruptions release large amounts of mercury, so scientists looked for traces of the element in rocks from an areacalled the Central Atlantic Magmatic Province that spans the U.S., Morocco and Nova Scotia today but was once a contiguous part of Pangea. They found increased levels corresponding with the extinction event at the end of the Triassic period and the start of the dinosaur-filled Jurassic one in five of six sites checked.

The volcanoes giveth... and the volcanoes taketh away. This might not be the only mass extinction caused by volcanoes. Some scientists think massive eruptions - not an asteroid - brought the dinosaur's reign to their end. Others even think it might have been both.