What appeared on earth first? neanderthals, homo habilis, homo sapiens, australopithecines

The earliest evidence for life found so far is in a 3.8 billion-year-old rock, the Isua sediments, found in western Greenland. The evidence for life in these rocks does not come from fossilized remains, but from a peculiar chemical signature of living organisms. These rocks were deposited on the surface of an oceanic crust on what was thought to be a deep ocean. So the Isua sediments are actually an ancient sea-floor.