Mammals Humans Vascular plants Shelly Origin of Earth invertebrates (4.6bya) 20%02/ Present 1 bya 4 bya Bacteria 0 Anoxygenic Algal phototrophic diversity Microbial lite forms only bacteria 3 ya Anoxic Earth(N2,CO2, Earth Origin of CHa atmosphere) is slowly Eukaryotes oxygenated Origin of cyanobacteria Copyright2009 Pearson Education,Inc..publishing as Pearson Benjamin Cummings.3 上海交通大学通识教育核心课程《微生物的世界》