Image: NATURE |
More than 500 salamander fossils, recently unearthed in China, offer a wealth of new information about the poorly documented origins of these animals and suggest that they emerged in Asia, according to a study published in today's issue of Nature.
"There has been a huge gap in the fossil record," Ke-Qin Gao of the American Museum of Natural History in New York and co-author of the study says. "The origin of salamanders was poorly documented; the fossil evidence was just inadequate. We only had fossils of the extant salamander families going back to the Tertiary, 65 million years ago."
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That has all changed now. Not only is the number of new fossils impressive, they are also 150 million years old¿or 85 million years older than the next oldest specimens¿and in very good shape(see image). "We were able to see all the stages of the life cycle, larvae and adults, as well as a range of different kinds of animals," Neil Shubin, a professor at the University of Chicago and Gao's co-author, says. "The exquisite condition of the fossils offers clues to evolutionary strategies¿larval details such as gills in adult animals, for example."
Unlike many other animal families, the basic design of salamanders hasn't changed much in millions of years. "Whether you look at a salamander you find under a rock in the local forest preserve or in a rock in China dating back 150 million years, they look alike," Shubin says. "In fact they look alike in great detail."
The large and diverse number of fossils found also makes a strong case that salamanders originated in Asia. "All the major primitive salamander families are now known to be present in Asia," Shubin notes. "The simple, take-home message is that there is an Asian origin for all salamanders."
