Spotted Salamander 
California Tiger Salamander 
Life Cycle 
Salamanders first appeared in the Jurassic. It is believed that they evolved from lpospondyles such as the microsauria. Salamanders are considered to be the least specialized of amphibians – mainly due to their conservative body plan. One interesting feature in salamander evolution is the secondary loss of bone and it’s replacement with cartilage.
Cladogram .jpg)
Salamander 2 fossil 
Recently, a large number of salamander fossils have been found in volcanic ash in China. The preservation was excellent -including many details of soft tissue anatomy.
Salamander 1 fossil 
Amphibians and Reptiles in Great Lakes Wetlands
China Ash Yields Salamander Evolution Secrets
Evolution: Library: Ring Species: Salamanders
Evolution of salamander life cycles: A major effect QTL …
Speciation, phylogeography and evolution of life history and …
Major fossil find reveals Asian origins of salamanders
University of Chicago Hospitals: New species of earliest-known salamanders found in China
Article 1 – Evolution of Modern Amphibians, by Lenny Frank
Filed under: Amphibians | Tagged: California Tiger Salamander |
Afarensis: Anthropology, Evolution, and Science 
An interesting debate was overlooked by some of your sources; the california tiger salamander Ambystoma tigrinum ca. is difficult to identify firmly. In the early part of the 20th century the buildinng of canals and flood protection zones and the loss of native habitat allowed an intermixing of several discrete populations (sorry at work and don’t have the source). What we call A.tigrinum ca. may be a hybrid of several species. Can anyone back me up on this?
It’s definately a ring species… I’ll have to do some checking and see what I can find out.