Francevillian biota

The Francevillian biota (also known as Gabon macrofossils or Gabonionta) is a group of 2.1-billion-year-old Palaeoproterozoic, macroscopic organisms known from fossils found in Gabon in the Palaeoproterozoic Francevillian B Formation, a black shale province. The fossils are regarded as evidence of the earliest form of multicellular life. The fossils were discovered by an international team led by the Moroccan-French geologist Abderrazak El Albani, of the University of Poitiers, France. While the fossils have yet to be assigned to a formal taxonomic position, they have been informally and collectively referred to as the "Gabonionta" by the Natural History Museum Vienna in 2014.

The fossil organisms are up to 12 cm in size. Their bodies were flattened disks with a characteristic morphology, including circular and elongated individuals. A spherical to ellipsoidal central body is bounded by radial structures. The fossils show three-dimensionality and coordinated growth. Cell-cell communication must be assumed as it existed before multi-cellularity arose.

A newer 2014 study by El Albani et al. describes multiple types of fossils with different morphologies. There are convoluted tubes, and "string of pearls"-like structures that terminate in a "flower". This is similar to dictyostelids, amoebal organisms that form multicellular assemblies to migrate. However, dictyostelids are terrestrial, not marine organisms so the structures cannot simply be dictyostelids. Among known fossiles, the Ediacaran Nemiana and Beltanelloides are most similar.

The findings come from shales of the Franceville basin with a high fossil density of up to 40 individuals per square meter. Presumably, the organisms survived at the bottom in shallow sea water in colonies.The geochemistry of the fossil site indicates that they lived on the sediment under an oxygenated water column of a prograding delta, and they might have engaged in aerobic respiration.

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