Rapid Recovery of Life at Ground Zero of the End Cretaceous Mass Extinction

Abstract

The Cretaceous-Paleogene (K-Pg) mass extinction eradicated 76% of species on Earth ^{1, 2} . It was caused by the impact of an asteroid ^{3, 4} on the Yucatán carbonate platform in the southern Gulf of Mexico at 66.0 Ma ⁵ which formed the Chicxulub impact crater ^{6, 7} . Following the mass extinction, recovery of the global marine ecosystem, measured in terms of primary productivity, was geographically heterogeneous ⁸ , as export production in the Gulf of Mexico and North Atlantic/Tethys took 300 kyr to return to Late Cretaceous quantities, slower than most other regions ^{8– 11} . Delayed recovery of marine productivity closer to the crater implies an impact-related environmental control, like toxic metal poisoning ¹² , on recovery times. Conversely, if no such geographic pattern exists, the best explanation for the observed heterogeneity is ecological, based on trophic interactions ¹³ , species incumbency and competitive exclusion by opportunists ¹⁴ , and “chance” ^{8, 15, 16} . Importantly, this question has bearing on the inherent predictability (or lack thereof) of future patterns of recovery in modern anthropogenically perturbed ecosystems. If there is a relationship between the distance from the impact and the recovery of marine productivity, we would expect recovery rates to be slowest in the crater itself. Here, we present the first record of foraminifera, calcareous nannoplankton, trace fossils, and elemental abundance data from the first ~200 kyr of the Paleocene within the Chicxulub Crater. We show that life reappeared in the basin just years after the impact and a thriving, high-productivity ecosystem was established within 30 kyr, faster than many sites across the globe. This is a clear indication that proximity to the impact did not delay recovery and thus there was no impact-related environmental control on recovery. Ecological processes likely controlled the recovery of productivity after the K-Pg mass extinction and are therefore likely to be significant in the response of the ocean ecosystem to other rapid extinction events.