A comparison of the new baboon skull (left) to previously unearthed specimens of P. angusticeps (center) and P. hamadryas (right). Photo by Wits University
MALAPA, South Africa, Aug. 19 (UPI) -- New analysis of an ancient ape skull unearthed in South Africa confirms the fossil belongs to Papio angusticeps, a species closely related to modern baboons.
Researchers say the skull may even be an example of the earliest known members of the modern baboon species, Papio hamadryas.
The skull was found by a team of U.S. and South African scientists at Malapa, the Cradle of Humankind World Heritage Site. It's believed to be more than two million years old.
Modern baboons are subdivided into six different populations, both species and subspecies, with habitat spreading across sub-Saharan Africa and the Arabian Peninsula. But the lineage doesn't trace neatly into the past.
Ancient baboon fossils have mostly been too fragmented to lead to firm conclusions about the divergence of the modern species from their ancient ancestors.
"According to molecular clock studies, baboons are estimated to have diverged from their closest relatives by 1.8 to 2.2 million years ago," Christopher Gilbert, a researcher at Hunter College, CUNY, said in a press release. "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 is the lead author of a new paper on the South African discovery, published in the journal PLOS ONE.
"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," Gilbert explained. "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."
Ape fossils are often used as aging benchmarks to more accurately date other fossils, especially at sites shared by apes and early hominins. The latest discovery not only adds clarity to the evolution of the modern baboon, but may also improve dating records.