Montpelier, Vt. – A scorpion stung David Sullivan on the back of his right leg, just below the knee, then continued up that leg and down the other, he believes, before getting him again in the shin.

The world’s oldest scorpions are thought to have led an aquatic life, but surprisingly, recently unearthed fossils are now hinting at a penchant for land. The remains of a new species, Eramoscorpius ...