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Rapid marine oxygen variability: Driver of the Late Ordovician mass extinction

Kozik, Nevin P.; Young, Seth A.; Newby, Sean M.; Liu, Mu; Chen, Daizhao; Hammarlund, Emma; Bond, David P.G.; Them, Theodore R.; Owens, Jeremy D.


Nevin P. Kozik

Seth A. Young

Sean M. Newby

Mu Liu

Daizhao Chen

Emma Hammarlund

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David Bond
Palaeoenvironmental Scientist and Schools Liason Officer

Theodore R. Them

Jeremy D. Owens


The timing and connections between global cooling, marine redox conditions, and biotic turnover are underconstrained for the Late Ordovician. The second most severe mass extinction occurred at the end of the Ordovician period, resulting in ~85% loss of marine species between two extinction pulses. As the only "Big 5" extinction that occurred during icehouse conditions, this interval is an important modern analog to constrain environmental feedbacks. We present a previously unexplored thallium isotope records from two paleobasins that record global marine redox conditions and document two distinct and rapid excursions suggesting vacillating (de)oxygenation. The strong temporal link between these perturbations and extinctions highlights the possibility that dynamic marine oxygen fluctuations, rather than persistent, stable global anoxia, played a major role in driving the extinction. This evidence for rapid oxygen changes leading to mass extinction has important implications for modern deoxygenation and biodiversity declines.


Kozik, N. P., Young, S. A., Newby, S. M., Liu, M., Chen, D., Hammarlund, E., …Owens, J. D. (2022). Rapid marine oxygen variability: Driver of the Late Ordovician mass extinction. Science Advances, 8(46), eabn8345.

Journal Article Type Article
Acceptance Date Sep 30, 2022
Online Publication Date Nov 18, 2022
Publication Date Nov 16, 2022
Deposit Date Oct 12, 2022
Publicly Available Date Nov 21, 2022
Journal Science advances
Electronic ISSN 2375-2548
Publisher American Association for the Advancement of Science
Peer Reviewed Peer Reviewed
Volume 8
Issue 46
Pages eabn8345
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Copyright © 2022 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY). is an open-access article distributed under the terms of the Creative Commons Attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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