Low O2 and Mo Levels in Ancient Oceans Delayed Evolution of Life by 2 Billion Years (image) University of California - Riverside Share Print E-Mail Caption Clinton Scott (left), the first author of the research paper, is a graduate student working in the laboratory of Timothy Lyons (right), a professor of biogeochemistry in the Department of Earth Sciences. Scott is seen holding a sample of black shale the researchers used in their analysis. Black shales are rich in organic matter and are repositories for molybdenum, with concentrations that vary with the amount of molybdenum in seawater. Credit Lyons lab, UC Riverside Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.