Figure 3From: A genomic timescale of prokaryote evolution: insights into the origin of methanogenesis, phototrophy, and the colonization of landA timescale of prokaryote evolution. Letters indicate nodes discussed in the text. The last common ancestor was arbitrarily placed at 4.25 Ga in the tree, although this placement was not part of the analyses. The grey rectangle shows the time prior to the initial rise in oxygen (presumably anaerobic conditions). Mtb: Methanothermobacter, Tab: Thermoanaerobacter, Tsc: Thermosynechococcus.Back to article page