One of the greatest survivors in all of Earth’s history was a humble creature named Lystrosaurus. It was a dog-sized animal whose peculiar lineage evolved about 270 million years ago, and looked like a cross between a pig and a lizard. Snub-faced and splay-legged, it was a burrower with powerful front legs who probably dug its own den every night. And somehow, it managed to survive the worst mass extinction the world has ever known.

About 250 million years ago, at the close of the Permian period, an enormous volcano called an igneous province started erupting in the region of the world that would one day be Siberia. At the time, this volcano was at the northern tip of a supercontinent