(i) Parapithecus: These are earliest fossil form of monkey, ape and man is available to date. The fossils are found in lower Oligocene epoch in Egypt. The old world monkeys are diverged from the main trunk of primate evolution in the Oligocene.

(ii) Propilopithecus: Another evolutionary line, developed from main trunk in Miocence about 10 million years ago give rise to gibbons in two stages named propliopithecus and pliopithecus.

(iii) Dryopithecus: it is considered as fossil ape and a common ancestor of great ape (orangutan, chimpanzee and gorilla) and man. These ancestral forms were living in the early Miocene, some 25 millions years ago. It is similar to chimpanzee except that leg and hands of approximately same equal length.

(iv) Proconsul: Dryopithecines were evolved into fossil named proconsul africanus. It was discovered from the Miocene in south Africa. Proconsul diverged to give rise chimpanzee and gorilla in Pliocene about 4 millions years ago. Around 2.3 millions years ago, chimpanzee and gorilla diverged from each other in the Pleistocene Epoch.

  
Human ancestral forms: The charactersitcs of different human ancestral forms is given in the Figure 10.5.  

(a) Ramapithecus: it was the primitive ape like primate, lived on tree and occasionally travelled and ate on ground. It survived life on nuts and food grains, as it lacks well developed cannines and molars. These ancestral forms extinct almost 7 million years ago.

(b) Australopithecus: These are considerd as first Ape-man. First report of these ancient forms on earth is 4-5 million years ago in South Africa. He was 1.05 meter high and was mainly living terrestrial creature with bipedal locomotion. There was no evidences that these ancestral forms can be able to made or used tools. The cranial capacity was 500 cm3 but had small canine and incisor teeth and short fingers. They can be able to walked in upright posture. 

 
(c) Homo Habilis: Australopithecus give rise to homo hibalis around 2 million years ago in Pleistocene. He was 1.5-1.8 meter high and had small cannies and light jaw. The available fossil data indicate the first usage of tools by these ancestral forms. The cranial capacity was 650-800cm3. He is more closure to the man like features than ape. He was carnivorous and hunted large animals. He was maintaining a social life, started living in caves and cared for young one.