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 upward 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?