In its 4.6 billion years circling the sun, the Earth has harbored an increasing diversity of life forms:for the last 3.6 billion years, simple cells (prokaryotes);for the last 3.4 billion years, cyano ...
In this timeline, Ma (for megaannum) means "million years ago", ka (for kiloannum) means "thousand years ago", and ya means "years ago".Hadean EonMain article: Hadean4000 Ma and earlier.Date Event4600 ...
This timeline of evolution of life represents current scientific theory outlining the major events in the development of life on planet Earth. In biology, evolution is any change across successive gen ...
