Quote:"For a time in the 1960s and '70s, Ramapithecus was thought to be a distinct genus that was the first direct ancestor of modern humans (Homo sapiens) before it became regarded as that of the orangutan ancestor Sivapithecus.
Simons’s theory was strongly supported by his student English-born American anthropologist David Pilbeam and soon gained wide acceptance among anthropologists. The age of the fossils (about 14 million years) fit well with the then-prevailing notion that the ape-human split had occurred at least 15 million years ago. The first challenge to the theory came in the late 1960s from American biochemist Allan Wilson and American anthropologist Vincent Sarich, who, at the University of California, Berkeley, had been comparing the molecular chemistry of albumins (blood proteins) among various animal species. They concluded that the ape-human divergence must have occurred much later than Ramapithecus. (It is now thought that the final split took place some 6 million to 8 million years ago.)
Wilson and Sarich’s argument was initially dismissed by anthropologists, but biochemical and fossil evidence mounted in favour of it. Finally, in 1976, Pilbeam discovered a complete Ramapithecus jaw, not far from the initial fossil find, that had a distinctive V shape and thus differed markedly from the parabolic shape of the jaws of members of the human lineage. He soon repudiated his belief in Ramapithecus as a human ancestor, and the theory was largely abandoned by the early 1980s. Ramapithecus fossils subsequently were found to resemble those of the fossil primate genus Sivapithecus, which is now regarded as ancestral to the orangutan; the belief also grew that Ramapithecus probably should be included in the Sivapithecus genus."
From: https://www.britannica.com/topic/Ramapithecus
