Xinhua News Agency, Lanzhou, August 27th Drought and little rain, desolate and magnificent Gobi, desert, this is the impression many people have of my country's northwestern region. But has it always been like this here? Back in time tens of millions of years ago, there was once lush vegetation and dense forests. giant rhinoceros , shovel elephant and other tropical and subtropical animals inhabited and proliferated here successively.
(Poster image provided by Hezheng Ancient Animal Fossil Museum)
Why did the Northwestern Region become what it is today? How did this change happen in the time latitude of tens of millions of years?
At and Zheng Ancient Animal Fossil Museum in Hezheng County, Linxia Hui Autonomous Prefecture, Gansu Province, experts found the answer from the fossil remains of prehistoric animals.
Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences Researcher Deng Tao is mainly engaged in the study of mammals, terrestrial strata and environmental evolution in the Late Cenozoic. He often travels between Linxia Prefecture, Gansu Province and Beijing. Because of the special basin topography in the Linxia area, a large number of complete ancient mammal fossils have been preserved. Today, the Hezheng Ancient Animal Fossil Museum has more than 30,000 fossil specimens.
Stratigraphic section of Hezheng area (photo courtesy of Hezheng Ancient Animal Fossil Museum)
These large numbers of fossil specimens are important clues to unlocking the "code" of climate change in Northwest China.
Deng Tao and his research team discovered that the fossils in the geological sediments of different ages in the Linxia Basin pointed to 4 different faunas that existed in the area. In chronological order, they were the giant rhinoceros fauna and the shovel tooth. Elephant fauna, three-toed horse fauna and real horse fauna. Each animal group corresponds to a different natural environment. "The survival of the fittest, the dominant animal group in each period can adapt to the environment at that time." Deng Tao said.
From this, we can "decrypt" how the climate and environment of Northwest China represented by the Linxia region, and even the inland regions of Central Asia, have undergone ups and downs in the past tens of millions of years.
This is the restored three-toed horse skeleton (photographed by Xinhua News Agency reporter Ma Sha)
Walking into the Hezheng Ancient Animal Fossil Museum, a huge restored statue of a prehistoric animal on the left attracts people’s attention. It has a long Long neck, shoulder height up to 5 meters when standing. This is the giant rhino, living between 42 million and 21 million years ago. It is a tall mammal that feeds on the leaves on the top of the canopy. "The giant rhinoceros could not move in the dense forest. It can be speculated that the natural environment in the northwest was dominated by sparse forest at that time." Deng Tao believes that the climate at that time was relatively warm and humid, even a bit hot.
A large number of shoveltooth skeletal fossils were unearthed in the Hezheng area. The museum has a shoveltooth skull from three to four months to more than 40 years old, and even the skeleton of a shoveltooth was restored. According to experts, the shoveltooth is the second large animal group found in Linxia after the giant rhinoceros. They lived in the global warm period and the temperature was at least 4 to 5 degrees Celsius higher than the current average temperature. The shovel-tooth elephant made a living by shoveling water weeds, indicating that there were lakes, rivers and dense forests in northern China at that time.
With the uplift of the Qinghai-Tibet Plateau and the end of the global warming period, the shoveltooth fauna was quickly replaced by the three-toed horse fauna. In the museum, the reporter saw a three-toed horse reconstructed skeleton. Unlike modern horses, it has 3 toes on each leg and is good at running in open areas. According to reports, the forest degradation and the rise of grasslands in the northwest at that time were particularly suitable for the survival of the three-toed horse population. "At that time, it was a bit similar to the current East African prairie , which was dry and hot." Deng Tao said.
This is a restored life scene of a three-toed horse (photographed by Xinhua News Agency reporter Ma Sha)
As time goes by 2.5 million years ago, a population called real horses appeared, and this is the fourth one in the Linxia Basin The dominant animal group that appears. As the world enters the ice age, the climate in the northwest has become more arid and cold. "There were a large number of carnivores during this period. They were the natural enemies of herbivores. The three-toed horse fauna, which was not as fast as real horses in running and eating, was no longer adapted to the environment at that time." Deng Tao explained that real horses are more similar to modern horses. , Each foot has only one toe, which makes the real horse run faster.
This is the reconstructed skeleton of the Eschman horse (a kind of real horse) (photo courtesy of the Hezheng Ancient Animal Fossil Museum)
"In Northwest China, the changes in fauna are not only closely related to the global climate, but also affected by the Qinghai-Tibet Plateau. The uplift is a geographical factor.” Deng Tao and his team found that giant rhinoceros fossils were unearthed on both the north and south sides of the Qinghai-Tibet Plateau, indicating that the plateau was far from uplifting to the current height and the giant rhino fauna could still Walk freely. "We speculate that the height of the uplift at that time was below 2,000 meters." Deng Tao said. By the time of the shoveltooth, there was no trace of the distribution of this population on the south side of the plateau, indicating that the plateau had been uplifted to a height that hindered the free migration of the shoveltooth. , "Maybe more than 3000 meters."
It is understood that scientists usually judge the climate and environment at that time based on the distribution of animals, body structure, height of tooth crowns, and food types. The pollen fossils and spore fossils of some plants can support this judgment.
"The Linxia Basin is a very special area. It is like a'plateau history', which fully records the climate change and the uplift process of the Qinghai-Tibet Plateau in the northwestern region," said Deng Tao. (End)
Xinhua News Agency reporters Hu Weijie, Yang Yating, Martha
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