The 2.1 Ga Old Francevillian Biota: Biogenicity, Taphonomy and Biodiversity – Plos one Juin 2014.

Biodiversity was already there 2 billion years ago

A new important article just published in the American journal PLoS One. The international team led by Abderrazak El Albani, describes the oldest known biodiversity on Earth. biodiversite

Gabon fossils 2.1 billion years. © CNRS Photothèque / Pr. A. El Albani – IC2MP – CNRS – Université de Poitiers.

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Have a look on the photos of gaboneese fossils

Abstract :

The Paleoproterozoic Era witnessed crucial steps in the evolution of Earth’s surface environments following the first appreciable rise of free atmospheric oxygen concentrations ~2.3 to 2.1 Ga ago, and concomitant shallow ocean oxygenation. While most sedimentary successions deposited during this time interval have experienced thermal overprinting from burial diagenesis and metamorphism, the ca. 2.1 Ga black shales of the Francevillian B Formation (FB2) cropping out in southeastern Gabon have not. The Francevillian Formation contains centimeter-sized structures interpreted as organized and spatially discrete populations of colonial organisms living in an oxygenated marine ecosystem. Here, new material from the FB2 black shales is presented and analyzed to further explore its biogenicity and taphonomy. Our extended record comprises variably sized, shaped, and structured pyritized macrofossils of lobate, elongated, and rod-shaped morphologies as well as abundant non-pyritized disk-shaped macrofossils and organic-walled acritarchs. Combined microtomography, geochemistry, and sedimentary analysis suggest a biota fossilized during early diagenesis. The emergence of this biota follows a rise in atmospheric oxygen, which is consistent with the idea that surface oxygenation allowed the evolution and ecological expansion of complex megascopic life.

Authors : Abderrazak El Albani, Stefan Bengtson, Donald E. Canfield, Armelle Riboulleau, Claire Rollion Bard, Roberto Macchiarelli, Lauriss Ngombi Pemba, Emma Hammarlund, Karim Benzerara, Alain Meunier, Idalina Moubiya Mouele, Sylvain Bernard, Philippe Boulvais, Marc Chaussidon, Christian Cesari, Claude Fontaine, Ernest Chi-Fru, Juan Manuel Garcia Ruiz, François Gauthier-Lafaye, Arnaud Mazurier, Anne Catherine Pierson-Wickmann, Olivier Rouxel, Alain Trentesaux, Marco Vecoli, Gerard J. M. Versteegh, Lee White, Martin Whitehouse, Andrey Bekker .

Read the article in Scientific American Jan 2015

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