In a surprising finding about the evolution of snakes, most snakes living on the surface today arose from ancestors that lived underground, U.S. scientists say. A study based on 44 genes and 161 species of lizards and snakes, one of the largest genetic data sets assembled for reptiles, shows almost all groups of snakes arose from within a bizarre group of burrowing blind snakes called scolecophidians. The finding implies snakes ancestrally lived underground and the thousands of snake species living today on the surface evolved from these subterranean ancestors, study leader John J. Wiens of the Department of Ecology and Evolution at Stony Brook University in New York reported in the journal Biology Letters. Traces of this subterranean ancestry can be seen in the anatomy of modern surface-dwelling snakes, the study said. \"For example, no matter where they live, snakes have an elongate body and a relatively short tail, and outside of snakes, this body shape is only found in lizards that live underground,\" Wiens said. \"Snakes have kept this same basic body shape as they have evolved to invade nearly every habitat on the planet -- from rainforest canopies to deserts and even the oceans.\"