Can the Cenozoic marine micropaleontological record be used to predict extinction?

Abstract:

Current estimates infer extinction rates to be at least 8x higher than the average background rate for the past 66 Ma. Therefore, characterising the biotic responses of organisms to climate change and heightened extinction susceptibility are increasingly important. The largest available archive of past extinction dynamics is the deep ocean microfossil record, which has been sampled over the past >50 years by a series of international drilling programs and platforms. The collected microfossil data is extensive and incredibly high-resolution, thus ideally suited for analysis of ancient extinction patterns across a range of spatio-temporal scales.

We focus here on Cenozoic planktonic foraminifera (PF) because their ecology is well defined (Aze et al. 2011), allowing for interrogation of biological responses across major deviations in climate state (e.g. Paleocene-Eocene Thermal Maximum, Eocene-Oligocene Transition) and preceding extinction. Analyses were performed using a new PF compilation dataset which we constructed, named Triton. Triton builds upon the successes of previous microfossil occurrence databases (e.g. Neptune, ForCenS), and contains > 400,000 individual PF occurrences, representing the largest occurrence dataset for any fossil group on the planet. The previous most complete dataset, Neptune, contained 121,647 records.

We first tested for high-resolution pre-extinction in situ adaptive ecological niche migration inferred through paired single-specimen geochemical and morphometric analyses using the coeval extinction of 3 members of the genus Dentoglobigerina as a case study.

We then investigated global biogeographic dynamics of all Cenozoic PF using Triton and demonstrate that distinct PF ecomorphological classes occupying distinct ecological niches show consistent biogeographic responses to Cenozoic climate perturbations.

Multi-scale analysis of pre-extinction dynamics improves our understanding of ancient marine ecosystem response to geologically sudden and dramatic climate excursions. The pre-extinction patterns we observe in the geological past may make it possible to identify modern ecosystems most at-risk to anthropogenic climate forcing, and subsequently focus conservation efforts before an ecological tipping point is reached.