Exquisitely-Preserved Basal Cryptobranchid Salamander from China

Description: The Daohuguo Beds on Inner Mongolia have yielded several Mesozoic salamanders related to those extant today. This one is a member of the Cryptobranchidae, the family to which the modern-day Asian giant salamander Andrias, and the Hellbender Cryptobranchus of the southern United States belong. Chunerpeton is the first Mesozoic salamander from this family which was previously only known as a fossil from the Paleocene. The fossil salamanders from these deposits go a long way to answering questions about the evolution of these remarkable amphibians. Phyletogentic analysis of the Urodeles shows that Asia is the origin of the clade, leading to the hypothesis that the basal salamanders radiated from the region. Some salamanders demonstrate neoteny, or the capability of reproducing while in what is apparently the larval state. Note the soft tissue outlines preserved, and three sets of gill structures, a telltale that this is not a larval form but a neotenic example. Neoteny is not all that uncommon among modern-day salamanders(some 40 species in 9 different families demonstrate this strategy), with the Mexican Salamander or Axolotl being a prime example. This means that it retains its gills and fins, and it doesn't develop the protruding eyes, eyelids and characteristics of other adult salamanders. It grows much larger than a normal larval salamander, and it reaches sexual maturity in this larval stage. The independent occurrence of neoteny in both Mesozoic and recent groups of salamanders makes parallel evolution of numerous morphological features an enduring feature of their history. Few such examples are ever available.