By Katharine Sanderson of Nature magazine The most direct evidence yet for ancient photosynthesis has been uncovered in a fossil of a matted carpet of microbes that lived on a beach 3.3 billion years ago. Frances Westall at the Centre for Molecular Biophysics, a laboratory of the French National Centre for Scientific Research (CNRS), in Orleans and her colleagues looked at the well-preserved Josefsdal Chert microbial mat–a thin sheet formed by layer upon layer of tiny organisms–from the Barberton Greenstone Belt in South Africa. These layers of ancient microorganisms grew at a time when Earth's atmosphere did not contain oxygen
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Microbial Mat Bears Direct Evidence of 3.3 Billion-Year-Old Photosynthesis