"Sometimes bad things come in small packages. A microbe that spewed humongous amounts of methane into Earth's atmosphere triggered a global catastrophe 252 million years ago that wiped out upwards of 90 percent of marine species and 70 percent of land vertebrates.
That's the hypothesis offered on Monday by researchers aiming to solve one of science's enduring mysteries: what happened at the end of the Permian period to cause the worst of the five mass extinctions in Earth's history.
The scale of this calamity made the one that doomed the dinosaurs 65 million years ago - a six-mile wide asteroid smacking the planet - seem like a picnic by comparison."
Will Dunham reports for Reuters April 1, 2014.