When Earth greened over.
Hand
Eric
E
D000818:Animals; D005075:Biological Evolution; D002244:Carbon / Q000378:metabolism; D019069:Cell Respiration; D018534:Earth, Planet; D017753:Ecosystem; D005580:Fossils; D049690:History, Ancient; D009792:Oceans and Seas; D010100:Oxygen / Q000032:analysis / Q000378:metabolism*; D010788:Photosynthesis; D010944:Plants / Q000378:metabolism*; D012623:Seawater / Q000737:chemistry
D002244:Carbon; D010100:Oxygen