66 million years ago, the dinosaurs that dominated the earth disappeared. What exactly caused the extinction of dinosaurs? Is it an asteroid hitting the Earth, climate change, or a massive volcanic eruption? The answer may not be so simple - scientists from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, the Institute of Geology and Geophysics of the Chinese Academy of Sciences, the China University of Geosciences (Wuhan) and other institutions carried out systematic research on dinosaur fossils in Shanyang Basin, Shaanxi Province, and proposed a new mechanism for the possible extinction of dinosaurs: during the Late Cretaceous, with the coordinated evolution of the natural ecosystem and dinosaurs themselves, The diversity of dinosaurs has undergone a continuous decline, which has reduced the environmental adaptability of this group of dinosaurs, leading to their inability to survive and recover from the environmental upheaval caused by major disasters such as volcanic eruptions or asteroid impacts, which ultimately led to extinction. The research results were published in the latest international comprehensive academic journal Proceedings of the National Academy of Sciences in the form of a cover article. The three main dinosaur types living in Shanyang Basin at the end of the Cretaceous Period: egg stealing dinosaur, duck billed dinosaur and tyrannosaur Zhao Chuangye, one of the main authors of this research Wang Qiang, associate researcher of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, explained: "To answer the mystery of dinosaur extinction, it is still necessary to rely on the time-space records of dinosaurs living on the earth, but the incompleteness and regional differences of continental stratigraphic records have caused difficulties in global comparison to answer this question." This study has conducted targeted research on the above issues. "Shanyang Basin in Shaanxi Province is one of the few continental basins in China that can study the mystery of dinosaur extinction in the Late Cretaceous Paleocene. The geoscientists led by Professor Xue Xiangxu of Northwestern University preliminarily established the continental stratigraphic framework of the Cretaceous Paleogene in this area, laying a foundation for relevant scientific research." Wang Qiang said that the scientists focused on the dinosaur egg fossils found in the basin this time. "Dinosaur eggs can not only reflect the breeding habits of dinosaurs, but also their enrichment and burial laws in the stratum can well reflect the ancient environment information during the dinosaur life." The research team systematically collected more than 1000 dinosaur eggs and eggshell specimens buried in situ in the late Cretaceous Shanyang Formation of the Shanyang Basin. The dinosaur eggs are mainly Yaotun giant eggs, Pingling laminated eggs, etc. The parent dinosaurs are egg stealers and duckbill dinosaurs, which is very consistent with the dinosaur types represented by dinosaur skeleton fossils in the Shanyang Basin. In addition, there are a few tyrannosaur bones in the basin. Wang Qiang said: "The research found that dinosaur eggs and dinosaur bones showed that the diversity of dinosaurs in the basin was at a relatively low level at that time." In order to determine the geological age of the strata where dinosaur fossils are located in the Shanyang Basin, the team carried out detailed research on magnetic stratigraphy, biostratigraphy and cycle stratigraphy in the Shanyang Basin, especially determined the "age" of the strata where dinosaur egg fossils were found with high accuracy, providing a reliable chronological basis for analyzing the changes in dinosaur diversity and its driving factors at the end of the Cretaceous. Wang Qiang said: "Chronological results show that the distribution of dinosaur fossils in the Shanyang Basin was 68.24 million to 66.38 million years ago, indicating that the diversity of dinosaurs in the Shanyang Basin was