Early oxygenation in shallow seas

Researchers report that the abundance of selenium (Se) and enrichment of 82Se, compared with 78Se, peaked 2.32 to 2.1 billion years ago in shallow marine shales from around the world, implying that the extent of moderately oxygenated habitats in the shallow oceans increased during this time; the authors suggest that these shallow seas might have harbored early stages of eukaryotic evolution, but oxygenation may have been too transient for substantial eukaryotic diversification, which was delayed until a billion years later. - Read at PNAS.org

Article #16-15867: “Selenium isotopes record extensive marine suboxia during the Great Oxidation Event,” by Michael A. Kipp, Eva E. Stüeken, Andrey Bekker, and Roger Buick.