of Californian salamander species and diurnal habits: relatively harmless species like the California slender salamander (Batrachoseps attenuatus) are nocturnal and are eaten by snakes, while the California newt has many large poison glands in its skin, is diurnal, and is avoided by snakes. Autotomy Some salamander species use tail autotomy to escape predators. The tail drops off and wriggles around for a while after an attack, and the salamander either runs away or stays still enough not to be noticed while the predator is distracted. The tail regrows with time, and salamanders routinely regenerate other complex tissues, including the lens or retina of the eye. Within only a few weeks of losing a piece of a limb, a salamander perfectly reforms the missing structure. Distribution and habitat Salamanders split off from the other amphibians during the mid- to late Permian, and initially were similar to modern members of the Cryptobranchoidea. Their resemblance to lizards is the result of symplesiomorphy, their common retention of the primitive tetrapod body plan, but they are no more closely related to lizards than they are to mammals. Their nearest relatives are the frogs and toads, within Batrachia. The earliest known salamander fossils have been found in geological deposits in China and Kazakhstan, dated to the middle Jurassic period around 164 million years ago. Salamanders are found only in the Holarctic and Neotropical regions, not reaching south of the Mediterranean Basin, the Himalayas, or in South America the Amazon Basin. They do not extend north of the Arctic tree line, with the northernmost Asian species, Salamandrella keyserlingii occurring in the Siberian larch forests of Sakha and the most northerly species in North America, Ambystoma laterale, reaching no farther north than Labrador and Taricha granulosa not beyond the Alaska Panhandle. They had an exclusively Laurasian distribution until Bolitoglossa invaded South America from Central America, probably by the start of the Early Miocene, about 23 million years ago. They also lived on the Caribbean Islands during the early Miocene epoch, confirmed by the discovery of Palaeoplethodon hispaniolae, found trapped in amber in the Dominican Republic. However, possible salamander fossils have been found in Australia at the Murgon fossil site, representing the only known salamanders known from the continent. There are about 760 living species of salamander. One-third of the known salamander species are found in North America. The highest concentration of these is found in the Appalachian Mountains