Australopithecines to Homonins a_afarensis_2.jpg toh._habilis_2.jpg
The first Homonids to come out of the tree and walk were known as Australopithecines. Australopihecines, such as Australopithecus ramidus, A. rnamensis, A. rethiopicus and the famous A. afarensis (Lucy), are believed to have evolved from a species known as Sahelanthropus tchadensis. S. tchadensis is commonly believed to be the common ancestor of Australopiticenes and Great apes, like Gorillas[of the Genus Gorilla], Chimpanzees and Bonobo[Pan], Orangutans[Pongo]. The only major find of this species is the Toumaï Skull. To some this is just an ancient ape skull.
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Toumaï Skull, S. tchadensis, A. afarensis, A. africanus

But for many this is the point were apes and humans separated. At the point of time were australopithecines evolved the Great Rift Valley was forming separating East Africa from West Africa, and the Himalayas were rising causing clouds to be blocked above India, were the huge amount of rain is known as the monssons.These two conditions caused East Africa to dry out and turn from forest to plain, making it a useful ability to walk and run. So at this point Great Apes and early humans parted and went their separate ways.

Early Australopithecines are believed to be the first creatures to walk upright on long distances. Australopithecines were rather short compared with the height of modern humans. A. afarensis stood at a height of around 110 to 140 centmetres tall. Infants were fully developed around 9-10 years.

The famous A. afarensis is believed to have evolved into A. aethiopicus and Australopithecus africanus, which is the widely accepted ancestor of Paranthopus boisie and P. robustus, and the possible ancestor of Homo rudolfensis, a forager and a scavenger. H. rudolfensis in some scientists opinions should, be a australopithecine instead of a homonin(See discussions to post your opinions).

P. boisei is the most specialized known homonid. P. boisei has a speciality on roots, tubers and corms. It's teeth show this. It's teeth also show that it occasionally ate fruit; a higher quality food source. But at this time the continent of Africa was drying out further and dry seasons would have been diffucult to live through unless you evolved new ways to get through the harshness of the enviroment.
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P.boisei, P. boisei Skull, H. rudolfensis, H. rudolfensis Skull

Another way of surviving had evolved. Not just foraging for low quality food, which would have kept species small and with small brains, but scavenging. H. rudolfensis had evolved to pick up signs of a carcass and used their ingenuity to butcher flesh and crack bone. But there also was another species that had evolved these qualities, not an australopithecine, but a homonin, Homo habilis.

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