Coupled sea-level and biodiversity dynamics during the Cambrian SPICE event

The prominent Cambrian Steptoean Positive Carbon Isotope Excursion (SPICE) stands as one of Earth’s largest carbon cycle perturbations, marked by widespread marine anoxia, climatic upheaval, and biotic turnover, yet the complete extent and interplay of these environmental changes remain unclear. Here, we integrate high-resolution astrochronology, carbonate carbon isotope records from the North China Block and marine species richness to investigate sedimentary and biogeochemical responses during the SPICE interval. Time series analysis reveals a distinct ~2-million-year sedimentary rhythm that aligns with cycles in reconstructed sea-level fluctuations and biodiversity dynamics. We show that sea-level changes preceded shifts in benthic species richness by 70 kyr, linking astronomically paced eustatic oscillations to marine redox fluctuations and concurrent biodiversity turnover. These findings establish pivotal constraints on ocean-climate interactions during this critical interval, elucidating Earth system resilience to extreme climatic and biogeochemical perturbations. Using astrochronology, Wang et al. estimate that relative sea-level change led benthic turnover by ~70,000 years during the late Cambrian SPICE event under their age model, supporting links among orbital forcing, marine anoxia and biodiversity loss.