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Re: Life on Earth - not dinosaurian, but interesting



JMB wrote:
> Hello honoured DMLers
>
> Just saw on TV news that _multicellular_ life has been brought back to 2.1
> billions (yes billions) years ago, just they don't know if it is animal or
> vegetal.
> Anyone got some more info about this?

Abderrazak El Albani, Stefan Bengtson, Donald E. Canfield, Andrey Bekker,
Roberto Macchiarelli, Arnaud Mazurier, Emma U. Hammarlund, Philippe
Boulvais, Jean-Jacques Dupuy, Claude Fontaine, Franz T. Fürsich, François
Gauthier-Lafaye, Philippe Janvier, Emmanuelle Javaux, Frantz Ossa Ossa,
Anne-Catherine Pierson-Wickmann, Armelle Riboulleau, Paul Sardini, Daniel
Vachard, Martin Whitehouse & Alain Meunier. 2010. Large colonial organisms
with coordinated growth in oxygenated environments 2.1 Gyr ago.
Nature 466:100?104. doi:10.1038/nature09166

Abstract

The evidence for macroscopic life during the Palaeoproterozoic era
(2.5?1.6 Gyr ago) is controversial1, 2, 3, 4, 5. Except for the
nearly 2-Gyr?old coil-shaped fossil Grypania spiralis6, 7, which may have
been eukaryotic, evidence for morphological and taxonomic
biodiversification of macroorganisms only occurs towards the beginning of
the Mesoproterozoic era (1.6?1.0 Gyr)8. Here we report the discovery
of centimetre-sized structures from the 2.1-Gyr-old black shales of the
Palaeoproterozoic Francevillian B Formation in Gabon, which we interpret
as highly organized and spatially discrete populations of colonial
organisms. The structures are up to 12 cm in size and have
characteristic shapes, with a simple but distinct ground pattern of
flexible sheets and, usually, a permeating radial fabric. Geochemical
analyses suggest that the sediments were deposited under an oxygenated
water column. Carbon and sulphur isotopic data indicate that the
structures were distinct biogenic objects, fossilized by pyritization
early in the formation of the rock. The growth patterns deduced from the
fossil morphologies suggest that the organisms showed cell-to-cell
signalling and coordinated responses, as is commonly associated with
multicellular organization9. The Gabon fossils, occurring after the
2.45?2.32-Gyr increase in atmospheric oxygen concentration10, may be seen
as ancient representatives of multicellular life, which expanded so
rapidly 1.5 Gyr later, in the Cambrian explosion.


Philip C. J. Donoghue & Jonathan B. Antcliffe. 2010. Early life: Origins
of multicellularity. Nature 466: 41?42 doi:10.1038/466041a [News & Views]

-- 
Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA