One of the theories has long been that enormous volcanic eruptions were the killers. A team of geologists published new data supporting the volcanic hypothesis:
In a new study published today in the journal Science, researchers say they have confirmed that eruptions large enough to bury the U.S. under 100 meters of lava occurred at the same time that vast numbers of plant and animal species disappeared from the fossil record. About 201 million years ago, tectonic forces started ripping the supercontinent known as Pangaea apart, said Terrence Blackburn, a geologist at the Carnegie Institution for Science in Washington, D.C., and lead author of the study. The underlying mantle rock melted, generating these large eruptions, he added. The rift, which eventually created the Atlantic Ocean basin, happened between sections of Pangaea that would go on to become North America and Africa. These huge eruptions, or flood basalt events, occurred during four periods over 600,000 years, but it’s the first bout of volcanism that contributed to the death of so many organisms, said Blackburn.
This brings home to me how lucky we are to be here. An event like this would be far beyond our adaptive capabilities, even now; had one taken place within the last 20 million years, our ancestors would have been wiped out.