Australopithecus, Homo Habilis, and Homo Erectus are all regarded as ancestors to modern man. The following quotes are from the Encyclopedia Britannica Online, August 2, 2005: Australopithecus: "Most paleoanthropologists believe that this genus is ancestral to modern human beings." Homo Habilis: "generally accepted as the earliest member of the genus Homo" (to which we Homo Sapiens belong) Homo Erectus: "thought to be the direct ancestor of modern Homo sapiens". Neanderthal Man is thought to have evolved, as we Homo Sapiens did, from Homo Erectus. Evidence from mitochondrial DNA indicates that we and the Neanderthals are seperate species. Homo Sapiens and Homo Neanderthalensis coexisted in Europe for several thousand years.(Wikipedia) Ramapithecus was first found as only an upper jaw and teeth. Its discoverer went way out on a limb in claiming it was a human ancestor. When more complete skeletal remains were found, it became clear that he was wrong, and ramapithecus was totally an ape.

Neandethal's lived during a period when modern man was living. All living things have a common ancestor. The popular statement "man descended from apes" is incorrect. The correct one is "Man and ape (primates) had a common ancestor ". That be about twenty million years ago and thirty if you add the baboons. Neandethal's are gone because they fell short in their birthrate by one baby a year. Seems trivial until time is added to the equation. Edit: This is a theory of many, not a proven fact.

Australopithecines *are* regarded as intermediate forms, just not all of them are regarded as being direct ancestors -- the early hominid family tree was more like a bush. It's just like your great-great-grandfather's brother was not likely to be a direct ancestor of yours, but was still probably representative of his generation. Neanderthals are our cousins. They were contemporary with both Homo heidelbergensis and Homo sapiens sapiens with substantial periods of overlap for both, indicating that their line split from ours before modern humans existed. They have been fairly definitively excluded from our direct ancestry on the basis of genetics -- mitochondrial DNA have been recovered from several Neanderthal skeletons and tested against human mtDNA for shared sequences. It was demonstrated that the mtDNA lines had diverged from each other significantly, and that the Neanderthal mtDNA had sequences that we would expect to find in Homo sapiense sequences if they were ancestral to us -- but that we did not find. There is a great deal of information to be found out about hominid ancestry, including a good listing of all the fossils, and a hominid timeline, at the Talkorigins.org archives: http://www.talkorigins.org/faqs/homs/ They also list all their sources, which are generally also accessible to the public. Edit: It seems I need to clarify my answer. Please note: The question was "why are australopithecines, neanderthal, etc. NOT regarded as intermediate evolutionary forms" -- the question is answered, neanderthals are not because they are not intermediary, they are a corollary line contemporary with the modern human form; and that australopithecines ARE intermediate, but not necessarily direct ancestors. Australopithecines are intermediary because they represent such a remarkable mix of primitive ape-like and "human" traits, and thus illustrate steps in the development of the modern human form -- whether they were directly ancestral to the modern human form, or merely closely related to the direct ancestor. This may be difficult for some of you to understand, but is nevertheless an accurate answer. It is just like, we do not claim that all the feathered dinosaurs of China were directly ancestral to modern birds -- many of them will have been corollary lines -- but they are nonetheless representative of and illustrative of the transitional stages between dinosaurs and birds because of the mix of dinosaur-like and bird-like features that they illustrate. Only one of them *had* to be a direct ancestor, but they were all related. As to *which* australopithecines are direct ancestors and which were not -- we do not believe any of the "robust" australopithecines could be direct ancestors, and they are now actually reclassified as "Paranthropus" in many circles. The gracile australopithecines such as africanus and afarensis are thought to be intermediate forms to humans, however, as is the more primitive anamensis -- but we do not know for sure if one, two or all of these were direct ancestors or merely close relatives of direct ancestors, as nobody sane claims that we have discovered all the fossil species which existed, or that, in the absence of genetic data, we can reconstruct an exact phylogeny free of any uncertainty. Nevertheless, these australopithecines display exactly the mixture of characteristics such as we would expect to see in the transition from apelike ancestor to modern human, and despite uncertainty as to exact relationship (i.e. are they our great-great-great-great-great-great-grandfathers, or our great-great-great-great-great-great-grandfather's brothers) they are still very much "intermediate". I realise that creationists will still turn around and say "this means you don't know if you have any human ancestors! You haven't proven it!" However, the fact that such an ancestry exists is the only rational explanation for the absence of fully human forms in ancient remains, and the presence of forms which display the mixture of human and more primitive features; hopefully readers will be able to follow this, as with why gracile australopithecines are classed as intermediary and neanderthals are not. (I realise that it is possible to hold the belief that God merely "poofed" into existance a series of similar looking species, wiped them out, and then "poofed" the next, slightly less primitive-looking ones into being, until eventually he "poofed" Homo sapiens into existance. However, this is not regarded as a rational explanation by science.) For further information on what is agreed to be ancestral to humans, please see my answer to question 31.

Neanderthal man is no longer considered a direct ancestor of man because a specimen was found which contained enough DNA fragments to do mitochondrial DNA analysis and it was concluded that it was not a direct ancestor of man from the results of this analysis. Australopithecus is still considered by some to be a direct ancestor, but there is some debate over this point. There are two types of Southern Ape, the robust and the gracile. The robust one has been discarded by most as an intermediary species, while the gracile one is still thought to be an ancestor. There are those that are termed lumpers, though, who think that there is great deal of variation within a species and would group the gracile and robust forms together as one species becasue of the similarities, which is why they are placed in the same group, Australopithicus. If a lumper were to say the robust form is not a direct ancestor and continue to see the gracile and robust forms as one group, he would also discard the gracile forms and thus all Australopithecines would be placed somewhere off to the side of his particular family tree for man, not leading directly to man. There is also a recent discovery of a fossil named by the discoverer as Orronin tugenensis (not sure of the spelling), or original man. This fossil is claimed to be much more similar to man than any Australopithecus, and yet it is older than Australopithecus. In fact at 6 million years old it is the oldest human-like fossil known, and is near the time that genetic analysis would place the common ancestor between man and ape. If this theory is correct then the less human like Australopithecines may not be a direct ancestor of man, but a side branch leading off to extinction or to living family of the gerat apes, and not a direct link to man, in a similar fashion as the Ramapithecines were discarded as intermediaries as they used to appear in some models of the family tree of man.