Microfossils of the Early Archean Apex chert: new evidence of the antiquity of life.

Entrez PubMed: "Eleven taxa (including eight heretofore undescribed species) of cellularly preserved filamentous microbes, among the oldest fossils known, have been discovered in a bedded chert unit of the Early Archean Apex Basalt of northwestern Western Australia. This prokaryotic assemblage establishes that trichomic cyanobacterium-like microorganisms were extant and morphologically diverse at least as early as approximately 3465 million years ago and suggests that oxygen-producing photoautotrophy may have already evolved by this early stage in biotic history."

Microfossils of the Early Archean Apex chert: new evidence of the antiquity of life. Schopf JW. Science. 1993 Apr 30;260:640-6.