The Late Cretaceous was a crucial period in earth's history, characterized by a greenhouse climate, several major geological events, and notably the Angiosperm Terrestrial Revolution. This biotic revolution led to a substantial and sustained increase in terrestrial diversity and changes in ecosystems. However, due to the lack of high-resolution richness curves for terrestrial organisms, our understanding of the evolution of life in the Late Cretaceous remains incomplete and upgraded.

In this study, 80 non-marine sections and drill cores containing ostracod fossils were compiled from China and subjected to rigorous data-quality control. Fourteen age control points, derived from zircon U-Pb dating, magnetic stratigraphy, and astronomical tuning were also used to establish precise chronological constraints on the resulting richness estimates. Using the Constrained Optimization  (CONOP) method, a high-resolution non-marine ostracod richness curve was constructed with an estimated temporal resolution of approximately 0.079 million years. This curve shows an overall increasing trend during the Late Cretaceous, with several prominent richness declines in the late Coniacian, the Santonian-Campanian boundary, and late Campanian.

These richness fluctuations are closely correlated with contemporaneous environmental changes, enhancing our understanding of ostracod richness and environmental dynamics during the Late Cretaceous. Our results also provide a framework for global comparisons of richness trends for the study interval.
 

CONOP,Species richness,East Asia,Radiation,Biocrisis