title: Oxygen appeared in the Earth's atmosphere 3 million years ago.
authors.forename: J F
authors.initials: JF
authors.lastname: Nunn
mesh_terms: D001272:Atmosphere; D000458:Cyanobacteria / Q000378:metabolism*; D007501:Iron / Q000737:chemistry; D010100:Oxygen
chemical_list: D007501:Iron; D010100:Oxygen