Timeline with prokaryotic fossil record. Timeline with geological events (A) and prokaryotic fossil record (B). (A) Formation of Earth , first evidence of continental crust , formation of continents , and glaciation events described in the Snowball Earth hypothesis . (B) The oldest conclusive cyanobacterial fossils are found in around 2.15 billion year old rocks. 1-7: Fossils from the Archean Eon [23,25,26,84-87]. 8: chroococcacean fossils ; 9: oscillatorian fossils . I-V: cyanobacterial fossils [18-20]. 10: eukaryotic fossils .
Schirrmeister et al. BMC Evolutionary Biology 2011 11:45 doi:10.1186/1471-2148-11-45