Earth’s biogeologic clock
The major lineages of pigments involved in anoxygenic photosynthesis arose before the development of oxygenic photosynthesis. The six major bacterial lineages had largely developed by the mid-Archean, around 3000 to 2800 Ma, and perhaps much earlier. The early biosphere passed through a stage during which even its photosynthetic populations depended exclusively on abiotic sources of reducing power.
Source: David J. Des Marais, “When Did Photosynthesis Emerge on Earth?” Science, 289, 1703 – 1705 (2000)