Call them "mudpuppies," "hellbenders," or "mud eels," salamanders are puzzling animals to most people. They come in forms that look like flattened fish with legs, like eels, like slimy lizards, or like lizards with toad-like skins. Their life history imitates the ancient evolutionary transition from aquatic to terrestrial vertebrates, though several groups remain permanently aquatic. Until now, no one has written about their ancient ancestors...