PARIS -- Scientists studying a partial jaw unearthed last year in Africa said Monday that analyses have shown it belongs to a previously unknown species of human ancestor.
The announcement, which shakes up several accepted notions about human origins, was hailed by other experts as a huge surprise.
"This is the beginning of a new history. From here, anything can happen," said Michel Brunet, a professor at the University of Poitiers who discovered the jaw.
Dubbed Australopithecus bahrelghazali, the species lived in Chad some 3 million to 3.5 million years ago. It is the first Australopithecus -- "southern ape" -- to be found as far west on the African continent.
Only eight other species of Australopithecus, found in eastern and southern Africa, were previously known.
Its location, age and distinctive characteristics may force students of human origins to re-examine much of what they regarded as truth, Brunet told reporters.
The jaw indicates that australopithecines, human predecessors that appeared after the evolutionary split away from the ancestors of modern apes, covered much greater territory than had been supposed.
Australopithecines gave rise to the group called Homo, which includes modern people.
Before the Chad finding, Australopithecines had been known from sites in South Africa and the Rift Valley in the east African nations of Ethiopia, Kenya and Tanzania. The Chad site lies 1,550 miles west of the valley.
The discovery of the new species so far from the valley complicates the task of paleontologists trying to trace the roots of humanity, since it had been thought certain that eastern Africa was the "cradle" of today's humans.
"I was very faithful to this idea. Now I'm not so sure," said Yves Coppens, chairman of the French Academy of Sciences' Prehistory and Paleoanthropology Department. "As far as surprises go, they don't get much bigger than this."
Brunet, who headed the Franco-Chadian mission that discovered the jaw and later identified it as belonging to a new species, said he had a hunch the surprises were just beginning.
"I'm sure that within the next 30 years we will have found other previously unknown species," he said.
Brunet said his team had already begun searching some 20 sites in the same region.
The discovery of the new species also means scientists can no longer be sure about when and where the evolutionary split between the apes and humans occurred.
"Abel," as Brunet's team named the jawbone's former owner, has a confusing set of characteristics that include a combination of the evolved human trait of molars with the three-root teeth typical of chimpanzees and other apes, Coppens said.
"It's an extraordinary casserole of the past. It's disturbing. But it's also a pleasure to discover yet again the whimsy of nature," he said.
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