Redox-gated extinction and radiation in early Paleozoic trilobites

Data associated with the manuscript: Abstract:Marine animal diversification during the early Paleozoic often coincided with major fluctuations in ocean redox chemistry, yet the macroevolutionary consequences of this volatility on macroevolutionary rates remain unresolved. Here, we integrated a global species-level trilobite fossil dataset with Bayesian birth–death models to reconstruct origination and extinction rates between 521–445 Ma. Our results show that diversification was episodic rather than gradual, with extinction peaks and suppressed origination coinciding with the Sinsk biotic crisis, the Steptoean Positive Carbon Isotope Excursion, and the Hirnantian Oceanic Anoxic Event. In contrast, the Great Ordovician Biodiversification Event followed a pronounced origination surge after redox recovery. Multivariate models demonstrate that atmospheric oxygen, temperature, and sea level cannot fully account for these excursions, whereas diversity dependence and continental fragmentation modulate background turnover. Together, these findings indicate that short-lived redox disruptions repeatedly closed and reopened the evolutionary window for radiation, effectively gating early Paleozoic trilobite macroevolution.