Large colonial organisms with coordinated growth in oxygenated environments 2.1 Gyr ago.
The evidence for macroscopic life during the Palaeoproterozoic era (2.5-1.6 Gyr ago) is controversial. Except for the nearly 2-Gyr-old coil-shaped fossil Grypania spiralis, 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). 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 organization. The Gabon fossils, occurring after the 2.45-2.32-Gyr increase in atmospheric oxygen concentration, may be seen as ancient representatives of multicellular life, which expanded so rapidly 1.5 Gyr later, in the Cambrian explosion.
El Albani
Abderrazak
A
Laboratoire HYDRASA, UMR 6269 CNRS-INSU, Université de Poitiers, 86022 Poitiers, France. abder.albani@univ-poitiers.fr
Bengtson
Stefan
S
Canfield
Donald E
DE
Bekker
Andrey
A
Macchiarelli
Roberto
R
Mazurier
Arnaud
A
Hammarlund
Emma U
EU
Boulvais
Philippe
P
Dupuy
Jean-Jacques
JJ
Fontaine
Claude
C
Fürsich
Franz T
FT
Gauthier-Lafaye
François
F
Janvier
Philippe
P
Javaux
Emmanuelle
E
Ossa
Frantz Ossa
FO
Pierson-Wickmann
Anne-Catherine
AC
Riboulleau
Armelle
A
Sardini
Paul
P
Vachard
Daniel
D
Whitehouse
Martin
M
Meunier
Alain
A
D001419:Bacteria / Q000166:cytology; D017753:Ecosystem; D056890:Eukaryota / Q000166:cytology; D005580:Fossils; D005681:Gabon; D019015:Geologic Sediments / Q000382:microbiology; D049690:History, Ancient; D010100:Oxygen / Q000378:metabolism*
D010100:Oxygen