Fossilized eukaryotes from 2.7 billion year old shales in Tanzania (original) (raw)

Some of the evidence for the existence of life in the Archean Eon (4.0-2.5 Ga) comes from ‘microfossils’ that are believed to be the mineralized remnants of simple prokaryotic lifeforms. They are spheroidal shaped and a few microns to tens of microns across and most likely represent early prokaryotic organisms. Here we describe spheroidal carbon structures that reach sizes of up to 540 microns from the 2.72 billion years ago (Ga) carbonaceous shales from the Lower Nyanzian Formation in the Geita Greenstone Belt of Tanzania. They are interpreted as microfossils based on their multi-chambered structures with pentagonal to hexagonal sectional geometries or floral forms, and chambers connected by regularly placed, tube-like structures that also connect inner chambers to the outside. The carbonaceous material in the walls is partly composed of disorganised kerogenous carbon with δ13C values averaging -44.6‰ that forms membranes coating a denser core of hematite enriched in P and transiti...