Tuesday, March 4, 2014

Untangling multiple fauna millions of years apart at the same site

Newly identified dinosaur fauna sheds light on evolution
It’s not a surprise that researchers originally assumed that everything that was turning up was effectively part of the same series of fossil beds. After all, such things were extraordinarily rare, and basically everything was preserved in volcanic ash. What were the odds that this was more than one fauna that just happened to overlap exactly geographically and in preservation type? The fact that many of the early discoveries were made by farmers or came through fossil dealers added to the confusion. Without knowing the exact origins of the material it was impossible to correlate the various fossil beds and outcrops that spread from the Chinese region of Inner Mongolia though the province of Liaoning and even into North Korea

However, in recent years it has become increasingly apparent that some of the material was rather older than had previously been thought. The new paper (of which I am an author) reviews the evidence establishing the geological age of these older fossils, and more importantly, suggests that they can be considered part of a new fauna. These older specimens come from a number of different localities, but they can be linked together by the presence of a salamander species. Radiometric dating work for numerous sites confirms an age of around 160m years old. We can thus use this species as a marker to help define what does and does not fall into this fauna and the dating suggests the existence of these animals over a relatively limited period of geological time.

Read the article here

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