98-9 An Inverse Approach to Determining the Drivers of Extinction Applied to the Late Ordovician and the Eocene-Oligocene Extinction Events

Session: Linking Biodiversity Loss to Environmental Stressors Through Integrated Approaches

Presenting Author:

Ryan Yohler

Authors:

Yohler, Ryan¹, Schuster, Erin², Mitchell, Charles E.³, Stockey, Richard G.⁴, Pohl, Alexandre⁵, Saupe, Erin E.⁶, Finnegan, Seth⁷

(1) University of California, Berkeley, Berkeley, CA, USA, (2) University at Buffalo, Buffalo, NY, USA, (3) University at Buffalo, SUNY, Dept. of Geology, Buffalo, NY, USA, (4) School of Ocean and Earth Science, University of Southampton, SOUTHAMPTON, United Kingdom, (5) Université Bourgogne Franche-Comté, Dijon, Bourgogne Franche-Comté 21078, France, (6) University of Oxford, Dept of Earth Sc, Oxford, United Kingdom, (7) UC Berkeley Integrative Biology, Berkeley, CA, USA,

Abstract:

Extinction events are typically associated with complex cascades of geologically rapid, dynamic, and near-simultaneous global environmental perturbations, making it sometimes challenging to determine which specific changes were most important in driving extinctions. Extinction selectivity patterns can provide critical insight into the drivers of extinction, but most selectivity analyses consider only a single, or few, hypothesized scenarios, highlighting a potential limitation due to the unknowable amount of missing information in the fossil record. We present a model-data comparison framework that permits broad exploration of multiple hypothetical global change scenarios and identifies those that are most consistent with observed paleogeographic occurrence data and extinction/survival patterns in the fossil record. Our approach couples the cGENIE Earth system model with probabilistic ecological niche models (ENMs) to predict where, if anywhere, a given species would be expected to persist under several global change scenarios. Model-data agreement is assessed by comparing these predictions to the observed patterns of extinction, survival, and suitable area shifts of animals during specific events. We have previously applied this approach to evaluate the record of planktonic graptolites during the controversial Late Ordovician Mass Extinction (LOME), finding much stronger support for global cooling as the main driver of extinction than warming during hypothetical changes of atmospheric CO₂. Our findings support the idea that the LOME is unusual among the “Big 5” mass extinctions in being linked to cooling rather than warming, but the relative patchiness and low temporal resolution of the Late Ordovician record inhibit direct comparison between our models and proxy records of paleoenvironmental change. To further evaluate support for global cooling as a driver of major extinction events, we extend our approach to include the more spatiotemporally resolved record of planktonic foraminifera through then Eocene-Oligocene transition. This transition marks the shift from an ice-free greenhouse world to an icehouse world, accompanied by the initial growth of the Antarctic icesheets, global temperature decline and widespread, protracted extinction. We again employ cGENIE and ENMs, now using the Triton database for planktonic foraminifera occurrence data. Owing to the higher spatiotemporal resolution of both proxy and occurrence information during this interval, we expand the range of modeled environmental change, evaluating potential shifts driven by hypothetical changes in atmospheric CO₂ and marine phosphate (PO₄).

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10832

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