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| Rukwapithecus (foreground) and Nsungwepithecus (background). MAURICIO ANTON |
Hot on the heels of the news that modern non-African peoples interbred with Neanderthals and Denisovans to form a possible human ring-species, showing that human speciation was in progress only a few thousand years ago, and the news that a seven million year-old earliest human fossil had been found showing intermediate 'transitional' characteristics between humans and chimpanzees, comes news that the earliest common ancestor of both apes and Old World monkeys has now been found. It's a delicious irony that today's slap in the face for primitive Creationists is news about the evolution of humans from monkeys.
The Scientist today has an article by Ed Yong about a letter published in Nature by N.J. Stevens et al., ("Palaeontological evidence for an Oligocene divergence between Old World monkeys and apes," Nature, http://dx.doi.org/10.1038/nature12161, 2013.)
Apes and Old World monkeys are prominent components of modern African and Asian ecosystems, yet the earliest phases of their evolutionary history have remained largely undocumented. The absence of crown catarrhine fossils older than ~20 million years (Myr) has stood in stark contrast to molecular divergence estimates of ~25–30 Myr for the split between Cercopithecoidea (Old World monkeys) and Hominoidea (apes), implying long ghost lineages for both clades. Here we describe the oldest known fossil ‘ape’, represented by a partial mandible preserving dental features that place it with ‘nyanzapithecine’ stem hominoids. Additionally, we report the oldest stem member of the Old World monkey clade, represented by a lower third molar. Both specimens were recovered from a precisely dated 25.2-Myr-old stratum in the Rukwa Rift, a segment of the western branch of the East African Rift in Tanzania. These finds extend the fossil record of apes and Old World monkeys well into the Oligocene epoch of Africa, suggesting a possible link between diversification of crown catarrhines and changes in the African landscape brought about by previously unrecognized tectonic activity in the East African rift system.The team found fragments of two different species; one of which is the oldest known Old World monkey (Nsungwepithecus gunnell) and the other of which is the oldest known hominoid (Rukwapithecus fleaglei). Both specimens were found in the same 25.2 million year-old stratum showing that diversification of the two families was well under way at that point in Earth's history.
As Ed Yong points out in The Scientist:
Nsungwepithecus sits on the stem of the Old World monkey clade, appearing before the last common ancestor of all living species within this group. Similarly, Rukwapithecus sits on the stem of the hominoid clade, within a group of obscure extinct primates called the nyanzapithecines.The significance of this find is that it brings the fossil evidence into line with the molecular evidence, placing diversification of these two primate families at about 26-27 million years ago in Africa, entirely in line with the theory of common descent with modification taking place over time in a very old Earth.
Stevens clarifies that although some previously discovered hominoids may have evolved earlier than Rukwapithecus, its fossils are the oldest yet discovered for this group. But David Begun, a paleoanthropologist from the University of Toronto, is not sure. He thinks that Kamoyapithecus - another Oligocene primate that lived 27 million years ago in Kenya - might also be a hominoid. He even wonders if it was the same animal as Rukwapithecus, since one is known from upper teeth and the other from lower ones.
It must be hard being a Creationist fraud when those nasty little facts keep hitting you in the face and making a monkey of you again. No wonder they are so skilled at ignoring facts because, just like ignoring tornadoes, everyone knows it makes them go away.
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