Distribution
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, and they are no more closely related to lizards than they are to mammals. Their nearest relatives are the frogs and toads, within Batrachia.
Caudates are found exclusively 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 species, Salamandrella keyserlingii occurring in the Siberian larch forests of Sakha and of the most northerly species in North America, Ambystoma laterale reaching no further than Labrador and Taricha granulosa not beyond the Alaska Panhandle. One-third of the known salamander species are found in North America. The highest concentration of these is found in the Appalachian Mountains region.
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