First geological boundary of dinosaur extinction found in China

Friday, September 2, 2011

The continental facies Cretaceouson-Paleogene stratigraphic boundary with International comparison standard had been found in Jiayin County, Heilongjiang province, scientists from 15 countries announced on Aug. 24.

That is to say, a geologic record can be found there that can perfectly pinpoint the extinction of organisms like dinosaurs, which happened 65.5 million years ago in today’s northeastern Asia.

"The continental facies Cretaceouson-Paleogene stratigraphic boundary found in Jiayin is also known as K-Pg boundary, with a thickness of 5 centimeters, and it's not only the first international point verified with accurate scientific evidence in China but also an achievement of important research about China’s international cooperation in geosciences," said Sun Ge, the vice chairman of the Palaeontological Society of China.

The Cretaceouson-Paleogene stratigraphic boundary is a stratum of evidence of a mass extinction that happened about 65.5 million years ago, which was represented by dinosaurs on land and ammonoids in the ocean.

During the eventful period, the earth and lives on it underwent a great change and left a record in the stratum. More than 70 percent of the organisms like dinosaurs, which controlled the earth and lived in the polar regions, underwent a mass extinction and a revival in new look and so did human beings.

For years, scientists searched for the Cretaceouson-Paleogene stratigraphic boundary all over the world. Up to now, 105 continental facies boundaries candidate points have been found, while there was no reliable K-Pg boundary point in China.

From 2002, taking Sun Ge as a representative, the scientists from China, the United States, the United Kingdom, Russia, Germany, Japan, Korea and Belgium, including D.L.Dilcher from the United States National Academy of Sciences, M.A.Akhmetiev from Russia Academy of Science and Dong Zhiming, a Chinese paleontologists, started to search for the continental facies strata interface of K-Pg in China by studying the paleobiology, geochemistry, paleomagnetism, chronostratigraphy and implementation drilling. They finally found the stratigraphic boundary beside a river in Jiayin County in Heilongjiang with the support from National Natural Science Foundation of China.

"In this region, we found the divide of the Mesozoic and Cenozoic of 5 centimeters in thickness in a stratum 200 meters in thickness. It perfectly recorded the reason why dinosaurs and other large numbers of paleontology species became extinct, and how, afterward, part of them revived as well as the environment on earth during that period," Dong said.

It has been said that during the past nine years, scientists found a lot of dinosaur fossils that were near the layer marking the eve of the sudden extinction and Wuyun Flora fossils appeared just after the extinction. Those fossils of ancient biota are not only relevant to other biota in which the K-Pg boundary was found but also have their own characteristics in organization and type.

D.L.Dilcher, a member of United States National Academy of Sciences said," for years, all of the scientists in the world focused on the small area in China, and now they can make a conclusion that this is a K-Pg boundary with reliable evidence, and it will be the standard in northeast Asia approved by the whole world.”

Jia Yin County is located in central Lesser Khingan Mountains in the northeast of Heilongjiang province. It has a long geologic history, and the earliest geologic record can be dated back to the Cambrian period at least 500 million years ago.

In 1902, "Mandschurosaurus" was first found in Jia Yin, and Jia yin became the earliest region where dinosaurs were discovered in China. According to the research of the paleontologist, this is also the place in which Chinese dinosaurs died out at the latest time period.

"Volcanic eruptions, the dropping sea level and the climate becoming cold are the main reasons of the dinosaurs' extinction in Jia Yin area, which is different from the extinctions that happened in North America and other regions. The confirmation of this boundary will play an important role in the study of the K-Pg in northeast Asia and even the whole world," said M.A.Akhmetiev from the Russian Academy of Science and a member of the discussion group.

It has been said that Jia Yin in China was recognized as the 95th candidate point among the105 international candidate points for the continental facies K-Pg boundary. This time is the formal international verification of the K-Pg boundary in Jia Yin.

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