The time of the split between humans and living apes used to be thought to have occurred 15 to 20 million years ago, or even up to 30 or 40 million years ago. Some apes occurring within that time period, such as Ramapithecus, used to be considered as hominids, and possible ancestors of humans. Later fossil finds indicated that Ramapithecus was more closely related to the orang-utan, and new biochemical evidence indicated that the last common ancestor of hominids and apes occurred between 5 and 10 million years ago, and probably in the lower end of that range. Ramapithecus therefore is no longer considered a hominid. The species here are listed roughly in order of appearance in the fossil record (note that this ordering is not meant to represent an evolutionary sequence), except that the robust australopithecines are kept together.Ardipithecus ramidusIt is the oldest known hominid species, found in the Middle Awash region of Ethiopia in 1994 by Tim White and dated at 4.4 million years. Most remains are skull fragments. Indirect evidence suggests that it was possibly bipedal, and that some individuals were about 122 cm (4'0") tall. The teeth are intermediate between those of earlier apes and A. afarensis, but one baby tooth is very primitive, resembling a chimpanzee tooth more than any other known hominid tooth. Other fossils found with ramidus indicate that it may have been a forest dweller. This may cause modification of current theories about why hominids became bipedal, which often link bipedalism with a move to a savannah environment. Australopithecus anamensisThis species was found in 1994 by Maeve Leakey in Kanapoi and Allia Bay situated in North Kenya. The material consists of 9 fossils, mostly found in 1994, from Kanapoi, and 12 fossils, mostly teeth found in 1988, from Allia Bay. Anamensis existed between 4.2 and 3.9 million years ago, and has a mixture of primitive features in the skull, and advanced features in the body. The...
