A partial skull of a fossil monkey specimen found in South Africa represents the earliest baboon ever found. The skull, which belongs to the Papio angusticeps species, also confirms that it was closely related to modern baboons.

Researchers found the skull during an excavation of a site called Malapa in the Cradle of Humankind World Heritage Site in that country, the same site where partial skeletons of the early hominin species, Australopithecus sediba, were found in 2010. They determined the baboon fossil's age to be between 2.026-2.36 million years.

"Baboons are known to have co-existed with hominins at several fossil localities in East Africa and South Africa and they are sometimes even used as comparative models in human evolution," Dr Christopher Gilbert, lead author of the study, said in a statement.

Modern baboons, Papio angusticeps, are found throughout sub-Saharan Africa and the Arabian Peninsula and generally divided into populations recognized as either species or subspecies. However, scientists have been unable to completely understand or come to a consensus regarding their origins in the fossil record. Gilbert explains that this lack of true understanding comes from fragmented fossils, the release said.

"According to molecular clock studies, baboons are estimated to have diverged from their closest relatives by ~1.8 to 2.2 million years ago; however, until now, most fossil specimens known within this time range have been either too fragmentary to be definitive or too primitive to be confirmed as members of the living species Papio hamadryas," Gilbert said in the statement. "The specimen from Malapa and our current analyses help to confirm the suggestion of previous researchers that P. angusticeps may, in fact, be an early population of P. hamadryas."

The partial skull did, however, display an anatomy consistent with modern-day baboons.

"If you placed a number of P. angusticeps specimens into a modern osteology collection, I don't think you'd be able pick them out as any different from those of modern baboons from East and South Africa," Gilbert added.

The estimated age of the fossil specimen also agrees with what scientists believe to be the initial appearance of modern baboons. As a result of their findings, evolutionary origins of this animal may be found--in addition to more accurate fossil-age estimates.

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