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178-1 Statistical evidence for the timing and duration of the Great Ordovician Biodiversification Event

Session: Paleontology, Diversity, Extinction, Origination

Presenting Author:

Jared Richards

Authors:

Richards, Jared¹, Nanglu, Karma², Ortega-Hernández, Javier³

(1) Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA, (2) Department of Earth & Planetary Sciences, University of California Riverside, Riverside, CA, USA, (3) Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA,

Abstract:

The Great Ordovician Biodiversification Event (GOBE) embodies the most dramatic increase of marine biodiversity and escalation of macroecological complexity during the early Phanerozoic. Despite its critical role, the precise timing and duration of the GOBE remain a matter of controversy. Numerous palaeobiological studies have attempted to quantify the GOBE based on estimates of species richness through time for various groups of marine organisms. However, these studies use fossil data restricted to specific geographic regions or employ disparate methodologies that preclude direct analytical comparisons. We present a meta-analysis of Ordovician biodiversity that integrates information from multiple temporal, geographic, and ecological scales. We collate 98 datasets from 54 publications to analyze temporally standardized rates of marine species biodiversity accumulation between the latest Cambrian and throughout the entire Ordovician using an effect-size approach. Our results indicate statistically significant high rates of sustained species accumulation that can be traced from the late Cambrian and until the Middle Ordovician, stabilization during the Late Ordovician and then a precipitous decline caused by the Late Ordovician Mass Extinction. Geographic scale (global vs regional) has no significant bearing on rates of biodiversification, with the only exception observed during the Dapingian-Darriwilian transition, supporting the hypothesis of mass dispersal of generalists during the Early Ordovician. Benthic and suspension-feeding organisms show high rates of biodiversity accumulation throughout most of the Ordovician (Tremadocian-Sandbian), whereas the diversification of nektonic, pelagic and predatory/scavenger organisms was mostly restricted to the Early Ordovician. Our findings statistically support the GOBE as a long-term radiation spanning most of the Ordovician Period.

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

doi: 10.1130/abs/2025AM-6172

Statistical evidence for the timing and duration of the Great Ordovician Biodiversification Event

Description

Session Format: Oral

Presentation Date: 10/21/2025

Presentation Start Time: 08:00 AM

Presentation Room: HBGCC, 305

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