life history in earth By xavi1996 3800 BCE Archean era http://www.bbc.co.uk/nature/history_of_the_earth/Archean 850 BCE Cryogenian period http://www.bbc.co.uk/nature/history_of_the_earth/Cryogenian 635 BCE Ediacaran period http://www.bbc.co.uk/nature/history_of_the_earth/Ediacaran 545 BCE Cambrian period http://www.bbc.co.uk/nature/history_of_the_earth/Cambrian 495 BCE Ordovician period http://www.bbc.co.uk/nature/history_of_the_earth/Ordovician
