The Texas rat snake was just as much of a speed demon as deadly vipers, challenging long-held notions about snake adaptations. When a snake strikes, it literally moves faster than the blink of an eye, whipping its head forward so quickly that it can experience accelerations of more than 20 Gs. Such stats come from studies of how a snake lunges, bites and kills, which have focused mostly on vipers, in part because these snakes rely so heavily on their venomous chomps. "It's the lynchpin of their strategy as predators," says Rulon Clark at San Diego State University. "Natural selection...