In recent years, Dr. Sha Jingeng and Dr. Fang Yanan, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, in cooperation with Professor Paul Olson of Columbia University, USA, have studied the continental Late Triassic to Early Jurassic of Haojiagou Section, Junggar Basin, Xinjiang, my country. High-resolution measurements and studies of the Roshi formation have found that the “volcanic winter” caused by the eruption of the Central Atlantic Super Igneous Province was the main cause of the mass extinction of terrestrial life at the end of the Triassic, and revealed for the first time that dinosaurs escaped the end of the Triassic The reason for the mass extinction of the species and its occupation of the Jurassic ecological theme: It has feathers with insulation function and has long been adapted to the polar cold climate. In the early morning of July 2, Beijing time, the research results were published online in the internationally renowned journal “Science Advances”.
Dinosaurs already adapted to the polar cold climate is how to discover? For the first time, the research team discovered ice raft deposits in deep lacustrine mudstones from the Late Triassic to Early Jurassic in the Junggar Basin, indicating that even during the polar-glacier-free greenhouse Earth period, there was seasonal ice formation at the poles. At the same time, the research team also found preserved essence in the lacustrine mudstone.beautifulFossilized dinosaur footprints. Together, these evidences suggest that dinosaurs from the Late Triassic to the Early Jurassic lived in polar regions and adapted to the seasonally cold climates of the polar regions.
Based on the phylogenetic scaffolding method, the research team concluded that dinosaurs were born with feathers, but these feathers were not used for flight, but for heat preservation. Before the end-Triassic extinction event, dinosaurs, especially herbivorous dinosaurs, were mainly distributed in the middle and high latitudes, while the low latitudes were dominated by herbivorous and carnivorous crocodilians. The research team believes that the primitive feathers with thermal insulation function can ensure that herbivorous dinosaurs can withstand the cold winters in the middle and high latitudes, and then enjoy the rich and stable plant resources in the middle and high latitudes exclusively. Plant resources in low latitudes are variable and unstable, and dinosaurs cannot compete with lower metabolic rate pseudocrocodiles due to their higher metabolic rates. False crocodiles cannot go to middle and high latitudes because they do not have feathers to keep out the cold.
For a long time, the scientific community generally believed that the eruption of the Central Atlantic Super Igneous Province was the main cause of the mass extinction event at the end of the Triassic. Global warming, ocean acidification, and lack of oxygen caused by massive amounts of carbon dioxide released by supervolcanic eruptions have long been blamed for the extinction of marine life, but global warming does not seem to explain the response of terrestrial organisms. After global warming, tetrapods and plants should migrate to high latitudes, but in fact, tetrapods in high latitudes, especially basal sauropod dinosaurs, not only survived the extinction event, but also migrated after the event. At low latitudes, the large protosaurus species in the tropics, including Phytosaurus and Pseudo-crocodiles, were almost completely extinct.
Therefore, the research team inferred that it was the “cold” of the “volcanic winter” that caused the mass extinction of terrestrial organisms, rather than the “heat” that traditionally believed, that is, the “volcanic winter” first caused by the supervolcanic eruption was the primary cause of the extinction of terrestrial organisms. factor. “Volcanic winter” refers to the phenomenon that after a large-scale volcanic eruption, the eruption material is transported in the stratosphere for a long time, which strongly blocks the sunlight that should be radiated to the earth’s surface, thereby causing the abnormal temperature drop of the atmosphere.
“Based on a long-term study of ice raft deposits and dinosaur footprint fossil records in my country’s Junggar Basin, we directly demonstrate that dinosaurs with feathered insulation have adapted to seasonal cold climates since their first appearance in the Late Triassic, which helped them hide After the ‘volcanic winter’ at the end of the Triassic period. Since the mass extinction event at the end of the Triassic period, the total number of dinosaurs has doubled, ushering in a 130-million-year-old era of land hegemony.” Fang Yanan said.
