Late Cretaceous paleoclimatic effects on the decreased dinosaur biodiversity in East Qinling

Climatic and environmental changes are the principal drivers affecting biota evolution. Therefore, reconstructing the paleoclimate and paleoenvironment background of terrestrial ecosystems is critical for discussing the evolution and extinction of biota. China is located in East Asia and is rich in dinosaur bone fossils and eggshells. However, the effects of climate and hydrologic environment in China on dinosaur biodiversity variation remain unclear. In East Qinling, several Late Mesozoicearly Cenozoic sedimentary basins preserve abundant Late Cretaceous dinosaur bone and egg fossils and Cenozoic mammal fossils. Thus, it is an ideal area to explore the relationship between the evolution of dinosaur biodiversity and regional climate changes. Here, we performed environmental magnetism and geochemistry at the Haoyanghe section of the Lingbao Basin to reconstruct the silicate weathering history and climate-hydrologic environment variation. The magnetic susceptibility and chemical weathering intensity reveal three stages of climatic-hydrological evolution. During ca. 74. 4 similar to 68. 0 Ma, the study area was in a stable hydrodynamic and deep-lacustrine environment with a gradually cold climate. From 68. 0 to 65. 8 Ma, the region became increasingly aridification, and the intensity of hydrological fluctuation strengthens. During ca. 65. 8 similar to 54. 7 Ma, the regional climate changed strongly, showing an enhanced dry-wet hydrological cycle. This study reveals the relationship between paleoclimate-hydrologic environment changes and dinosaur population evolution, suggesting that the climatic aridity and increased hydrologic fluctuation at the end of the Late Cretaceous (ca. 68 similar to 66 Ma) may be the main driving factor for the low biodiversity and extinction of the dinosaurs in East Qinling. Our study provides new data support for further understanding of the co-evolution of biology and environment.