Quantifying the evolutionary turnover across the K-T boundary catastrophic planktic foraminiferal extinction event at El Kef, Tunisia

Abstract

Four metrics (extinction ratio, speciation ratio, taxonomic flux and volatility) were used to quantify the planktic foraminiferal extinction and evolutionary pattern across the Cretaceous-Tertiary (K-T) boundary at El Kef (Tunisia). They revealed a stasis episode in the terminal Maastrichtian, a K-T catastrophic mass extinction and a post-K- T evolutionary radiation. This pattern was also correlated with geo-chemical and isotopic data. The impact evidence and the decrease in CaCO3 and δ13C coincide with a period of high evolutionary volatility and significant changes in the taxonomic flux which are both very compatible with the impact theory.