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Atmosphere–ocean oxygen and productivity dynamics during early animal radiations

Author(s): Dahl, Tais W; Connelly, James N; Li, Da; Kouchinsky, Artem; Gill, Benjamin C; et al

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Abstract: The proliferation of large, motile animals 540 to 520 Ma has been linked to both rising and declining O2 levels on Earth. To explore this conundrum, we reconstruct the global extent of seafloor oxygenation at approximately submillion-year resolution based on uranium isotope compositions of 187 marine carbonates samples from China, Siberia, and Morocco, and simulate O2 levels in the atmosphere and surface oceans using a mass balance model constrained by carbon, sulfur, and strontium isotopes in the same sedimentary successions. Our results point to a dynamically viable and highly variable state of atmosphere–ocean oxygenation with 2 massive expansions of seafloor anoxia in the aftermath of a prolonged interval of declining atmospheric pO2 levels. Although animals began diversifying beforehand, there were relatively few new appearances during these dramatic fluctuations in seafloor oxygenation. When O2 levels again rose, it occurred in concert with predicted high rates of photosynthetic production, both of which may have fueled more energy to predators and their armored prey in the evolving marine ecosystem.
Publication Date: 9-Sep-2019
Citation: Dahl, Tais W., James N. Connelly, Da Li, Artem Kouchinsky, Benjamin C. Gill, Susannah Porter, Adam C. Maloof, and Martin Bizzarro. "Atmosphere–ocean oxygen and productivity dynamics during early animal radiations." Proceedings of the National Academy of Sciences 116, no. 39 (2019): 19352-19361. doi:10.1073/pnas.1901178116.
DOI: doi:10.1073/pnas.1901178116
ISSN: 0027-8424
EISSN: 1091-6490
Pages: 19352 - 19361
Language: eng
Type of Material: Journal Article
Journal/Proceeding Title: Proceedings of the National Academy of Sciences of the United States of America
Version: Final published version. This is an open access article.

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