Why is the dinosaurs extinct?The research team of the Dudo University put forward a new understanding

Dinosaurs are the most well -known paleomantic creatures in the public. What caused the dinosaurs 66 million years ago? For a long time, this has always been a topic of debate in the scientific community. The asteroid impact and large volcanic outbreak are the most representative views. Recently, scientific research teams consisting of personnel such as the Institute of Ancient Spine Animals and Ancient Human Research Institute of the Chinese Academy of Sciences and the Institute of Geology and Geophysics of the Chinese Academy of Sciences have achieved new paleontology and age studies on the system carried out by the Shaanxi Shanyang Basin. Progress put forward a new understanding of the mystery of dinosaurs. Studies believe that the decrease in dinosaurs' diversity in the late white world is likely to be another important reason for dinosaurs.

The results of the research are based on the title of "Dinosaur's Low Diversity Before the 2 million years before its extinction", and published it in the cover article in the "PNAS" (PNAS).

"To answer the mystery of dinosaur extinction, the core is the time and space record of dinosaurs to survive on the earth." According to Dr. Han Fei, the first author of the paper, dinosaur eggs can not only reflect the breeding habits of dinosaurs, but also The law of enrichment burial can also reflect the ancient environment information of dinosaurs during the survival period.

Figure 1 Yaotun giant egg produced in the Shanyang Basin

The research team took 7 years. Among the upper white crickets in the Shanyang Basin in Shangluo, Shaanxi, my country, the system collected more than 1,000 pieces of dinosaur eggs and egg shell specimens buried in situ (Figure 1). Studies have found that the types of dinosaurs in the Shanyang Basin are mainly Yaotun giant eggs, long -shaped and long eggs and Pingling stack eggs. The mother dinosaurs are egg -stolen dragons and duckbill dragons. The type of dinosaurs represented by skeletal fossils is very consistent (Figure 2). Dinosaur eggs and dinosaurs showed that the dinosaurs in the basin at that time were at a relatively low level.

Figure 2 The three main types of dinosaurs of the Shanyang Basin at the end of the Baiji Period: Egg Dragons, Duck Both Dragon and Tyrannosaurus (Zhao Chuangi)

Figure 3 shows the rock columns (A and B) of the Shanyang Basin, the magnetic polar sequence (C), the astronomical tuning result (D), the distribution of dinosaur fossils (E), and the marine oxygen isotope Change (F and G), indicating that the dinosaurs in the basin have low diversity during the 2 million years before its extinction, and the changes in ancient climate, especially temperature have an important impact on the diversity of dinosaurs.

In order to determine the geological age of the strata where the dinosaur fossil is located in the Shanyang Basin, the team carried out detailed magnetic stratigraphic, biological stratigraphic and rotating stratigraphic studies in the Shanyang Basin, so as to obtain 44 continuous dinosaur egg fossil layer of Shanyang Basin High -resolution age (Figure 3). The results of the age of the age show that the time limit of dinosaur fossils in the Shanyang Basin is 68.24 million to 66.38 million years ago. It shows that the dinosaur diversity in the Shanyang Basin has been at a relatively low level during its extinction of about 2 million years.

Figure 4 Figure 4 shows the changes in the dinosaur diversity in the east of Qinling's east of Qinling, showing that the dinosaur diversity decreases around 72 million years. Figure C shows the current global distribution of dinosaur fossils discovered 66 million years ago. It shows that dinosaur fossils are mainly distributed in western North America and East Asia. The dinosaur fossils found in Qinling area will be very important to supplement the global dinosaur fossils.

Comprehensive dinosaur fossils found in the other late Baiyu Basin in the east of Qinling, as well as the dinosaur fossils found in Laiyang, Shandong, Nanxiong, Guangdong, and the researchers have found that the dinosaur diversity of China has a significant reduction trend in 72 million years. There are similarities between distribution characteristics, so the study believes that the decrease in dinosaur diversity in the late white world is likely to be a global phenomenon (Figure 4).

The results of this study provided a new basis and perspective for the process and mechanism of understanding the extinction of dinosaurs. Dinosaurs belong to ovarian animals, and the success rate of dinosaur eggs directly determines whether the flourishing of the dinosaur population. The incubation of dinosaurs requires the appropriate temperature, humidity and even carbon dioxide concentration. Therefore, this study believes that during the late white cymbal period, with the synergistic evolution of the natural ecosystem and the dinosaur itself, the dinosaur diversity has continued to decline, reducing the environmental adaptability of the dinosaur group, and resulting in the unable to obey the obedience. The survival and recovery of environmental dramas caused by major disasters such as the outbreak of the Degan volcano or asteroid impact, which eventually moved towards extinction.

Dr. Han Fei, Professor Wang Hua Pei of our school, is the first author of the paper, and the associate researcher of Wang Qiang of the Institute of Ancient vertebrates and the Institute of Ancient Human Research of the Chinese Academy of Sciences is the author of the communications. The study was jointly funded by the National Natural Science Foundation of China and the leadership of the Chinese Academy of Sciences.

Wen | Wang Junfang

WeChat editor | Zhao Jingxuan

Review ｜ Wei Haiyong Wang Junfang

- END -