BEIJING, April 17 (Xinhuanet) -- An international team of scientists has discovered 4.1-million-year-old fossils in eastern Ethiopia that fill a missing gap in human evolution, according to the latest Nature.

Scientists see an evolutionary link between newly found teeth of 4.1-million-year-old Au. anamensis, left, and previously discovered teeth of 3.3-million-year-old Au. afarensis, right. (Photo: sciencenews.org)

    A team led by anthropologist Tim D. White, co-director of Human Evolution Research Center at University of California at Berkeley, unearthed 31 fossils of Australopithecus anamensis, an ape-man creature that walked on two legs. The finds, from at least eight individuals, consist primarily of teeth and jaws, but include foot and hand bones and much of an upper right-leg bone.

    The species, Australopithecus anamensis, is not new, but its location is what helps explain the giant leap from one early phase of human-like development to the next, the scientists say.

    All eight species were found in a region called the Middle Awash. "It's like 12 frames of a home movie, but a home movie covering 6 million years," said White.

    Fossils in the region cover three major phases of human development. "The key here is the sequences," White said. "It's about a mile thickness of rocks in the Middle Awash and in it we can see all three phases of human evolution."

    Modern man belongs to the genus Homo, which is a subgroup in the family of hominids. What evolved into Homo was likely the genus Australopithecus, once called "man-ape," which includes the famed 3.2 million-year-old "Lucy" fossil found three decades ago.

    A key candidate for the genus that evolved into Australopithecus is called Ardipithecus. And the latest finding is important in bridging - but not completely - the gap between Australopithecus and Ardipithecus.

    Anatomical similarities indicate that Australopithecus evolved directly from Ardipithecus ramidus, between 4.4 million and 4.1 million years ago, the researchers. By 3.6 million years ago, they add, Australopithecus anamensis had evolved into Australopithecus afarensis, the species that includes the partial skeleton "Lucy."

    The new finds come from two Middle Awash sites, Aramis and Asa Issie. The fossil discoveries occurred between November 1994 and December 2005. The finds extend the known range of Australopithecus anamensis by about 600 miles to the northeast of two Kenyan sites where another team reported finding remains of the species in 1995.  

    While it's looking more likely, it is not a sure thing that Ardipithecus evolved into Australopithecus, White said. The finding does not completely rule out Ardipithecus dying off as a genus and Australopithecus developing independently. Enditem

    (Agencies)