1.1-Billion-Year-Old Porphyrins Establish a Marine Ecosystem Dominated by Bacterial Primary Producers
1.1-billion-year-old porphyrins establish a marine ecosystem dominated by bacterial primary producers N. Guenelia,1, A. M. McKennab, N. Ohkouchic, C. J. Borehamd, J. Beghine, E. J. Javauxe, and J. J. Brocksa,1 aResearch School of Earth Sciences, Australian National University, Canberra, ACT 2601, Australia; bNational High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310-4005; cDepartment of Biogeochemistry, Japan Agency for Marine–Earth Science and Technology, 237-0061 Kanagawa Prefecture, Yokosuka, Natsushimacho, Japan; dGeoscience Australia, Symonston, ACT 2609, Australia; and eDepartment of Geology, Unité de Recherche Geology, University of Liège, 4000 Liege, Belgium Edited by Andrew H. Knoll, Harvard University, Cambridge, MA, and approved June 8, 2018 (received for review March 6, 2018) The average cell size of marine phytoplankton is critical for the the molecular fossils of biological lipids, can provide comple- flow of energy and nutrients from the base of the food web to mentary information about primary producers. For example, higher trophic levels. Thus, the evolutionary succession of primary hydrocarbon fossils of carotenoid pigments extracted from sed- producers through Earth’s history is important for our understand- imentary rocks have been used to detect phototrophic green ing of the radiation of modern protists ∼800 million years ago and (Chlorobiaceae) and purple sulfur bacteria (PSB) (Chromatia- ∼ the emergence of eumetazoan animals 200 million years later. ceae) in 1,640-My-old marine ecosystems (4, 5), while the con- Currently, it is difficult to establish connections between primary centration of eukaryotic steranes, relative to bacterial hopanes, production and the proliferation of large and complex organisms may provide basic information about the ecological relevance of because the mid-Proterozoic (∼1,800–800 million years ago) rock Precambrian algae (6).
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