China Ash Yields Salamander Evolution Secrets

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"These finds point to Asia as a crucible for the early evolution of salamanders," said Shubin. "It shows that much of the major evolutionary changes in salamanders likely happened very early in their known evolutionary history. It also shows that remarkably little anatomical change has happened over the past 160 million years or so."

Chunerpeton tianyiensis and its modern equivalents like the North American hellbender (Crytobranchus) and the Asian giant salamander (Andrias) belong the salamander family known as the Cryptobranchidae, one of the two most primitive groups of salamanders.

The other primitive group of salamanders is known as the Hynobiidae. They are small- to medium-sized salamanders found throughout Asia.

"Cryptobranchids and hynobiids have long been suggested as the most primitive of the living salamander groups," said Carroll. "Their divergence, which must pre-date these particular fossils from China, must have preceded the appearance of all the other living salamander families."

Putting this in perspective, Carroll says modern salamanders essentially appeared early in the history of the dinosaurs and that some of the more primitive families of salamanders have changed very little since that time.

Shubin says that salamanders have been able to survive for such a long time period with relatively little evolutionary changes because they are generalists. "They have apparently hit on a very stable ecological and evolutionary strategy very early in their evolutionary history," he said.

Salamander Evolution

Scientists like Shubin, Gao, and Carroll say they are attracted to the study of salamanders because the amphibians give them a window to see how evolutionary mechanisms work.

Salamanders are more than 160 million years old, they have learned to live in a variety of environments, they have one of the largest genomes of any known animal, and researchers know quite a bit about their variation, said Shubin.

"Put all this together and it means we can understand how evolutionary changes to genes and development produce changes in anatomical features such as heads, limbs, tails," he said.

Of practical interest to humans, said Carroll, is the salamander's ability to regenerate limbs. This characteristic is unique among vertebrates. "It suggests the possibility that we may learn something of this capacity from salamanders that could be applied in the case of severe limb damage," he said.

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