Temporal range: 3500 mya – Recent
Chroococcales (suborders-Chamaesiphonales and Pleurocapsales)
Nostocales (= Hormogonales or Oscillatoriales)
Cyanobacteria are a taxon of bacteria which conduct photosynthesis. They are not algae, though they were once called blue-green algae. It is a phylum of bacteria, with about 1500 species. In endosymbiont theory, mitochondria are descended from cyanobacteria. Their DNA profile is evidence for this.
The ability of cyanobacteria to perform oxygenic photosynthesis is highly significant. The early atmosphere on Earth was largely reducing, that is, without oxygen. The cyanobacteria in stromatolites were the first known organisms to photosynthesis and produce free oxygen. After about a billion years, the effect of this photosynthesis began to a huge change in the atmosphere. The process, called the Great Oxygenation Event, actually took a long time. Eventually, it killed off most of the organisms which could not live in oxygen, and led to the kinds of environment we know today, where most organisms use and need oxygen.
Other pages [change]
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- Knoll, Andrew H. 2004. Life on a young planet: the first three billion years of evolution on Earth. Princeton, N.J. ISBN 0-691-12029-3
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- Heinrich D. Holland: The oxygenation of the atmosphere and oceans. In: Phil. Trans. R. Soc. B, vol. 361, 2006, p. 903–915 http://rstb.royalsocietypublishing.org/content/361/1470/903.full.pdf