Full Australopithecus Fossil Found in South Africa
Washington Post Foreign Service
Thursday, December 10, 1998; Page A1
JOHANNESBURG, Dec. 9 – A nearly complete skeleton of one of the oldest apelike ancestors of humans – a creature who apparently swung in trees but also walked upright – has been discovered encased in a 3.5-million-year-old rock formation inside a South African cave, scientists here announced today.
Excavating in the Sterkfontein Caves, one of the world's richest fossil sites, researchers from Johannesburg's University of the Witwatersrand discovered parts of the skeleton over the course of several months culminating in September, when their chisels uncovered the creature's cranium, intact jaws and teeth.
There had never been more than partial fossil evidence from any individual specimen of Australopithecus ("southern ape"), the bipedal hominid believed to be the immediate evolutionary predecessor of early Homo, the first humans.
That is why the partially unearthed new find, whose exact species is still uncertain, has galvanized experts around the globe.
"It's very exciting," said Rick Potts, director of human origins at the Smithsonian Institution's National Museum of Natural History. "If in fact we do have a complete or nearly complete skeleton, we're going to learn an awful lot more by studying it rather than reconstructing Australopithecus from fragments."
"The find is extremely important," said Bill Kimbel, science director of the Institute of Human Origins at Arizona State University in Tempe. "Primarily, that's because of the rarity of well-preserved skulls that are associated with skeletal remains in the hominid record of that age."
Most experts agree that approximately 5 million years ago an evolutionary line that eventually led to human beings began to diverge from the ancient apes. Somehow an apelike creature began to walk on two legs. The first well-defined group with those characteristics is the Australopithecines, which begin to show up in the fossil record about 4 million years ago. Several species are known, although the exact number, like so much else about early human evolution, is a matter of debate.
They were small by modern human standards: Adult skeletons suggest a height around 3½ to 4½ feet and a weight between 60 and 120 pounds. The face was much flatter than in humans, with exceptionally strong jaws. The arms were much longer than ours, reaching nearly to the knee.
Two of the most familiar species are Australopithecus afarensis (of which the Ethiopian specimen named "Lucy" is the prime example) and A. africanus, of which the classic examples are from South Africa. It is not clear whether one species preceded the other, whether they coexisted, or which – if either – was the direct ancestor of the first humans. It has generally been assumed that A. afarensis is probably the older species, but the new discovery may challenge that.
Australopithecines were the closest thing to humans until about 2.4 million years ago, when a new kind of creature called Homo first appears in the fossil record. (Stone tools begin to show up at the same time.) Again, there are several known species, beginning with H. habilis, and proceeding through H. erectus and numerous others, according to most experts. It is not until very recently – about 100,000 years ago – that there is the first convincing evidence of our species, Homo sapiens.
The gender of the South African hominid is not known, but it was a mature adult about four feet tall. It lived in what was then a heavily forested region near the modern-day city of Krugersdorp, about 30 miles west of Johannesburg, the researchers said at a news conference today.
"It clearly was a creature that had sprung loose from the trees," said Philip Tobias, professor emeritus of anatomical sciences at Witwatersrand and member of the team led by Ron J. Clarke. Tobias said he believes that the hominid apparently had "arboreal habits coupled with terrestrial habits."
Many scientists are skeptical of that claim, Arizona State's Kimbel noted. But the Smithsonian's Potts said that the creature's presumed ability to be at home in trees and on the ground could be a "hallmark of one of the characteristics that define our family tree: versatility."
Clarke and his team described how their "paleo-detective" work led to the discovery. "This story, like all good detective stories, begins with a death," he said.
The hapless hominid apparently fell into an underground cave and died. It lay face down and encased in the earth for more than 3 million years and was gradually covered by limestone.
In the 1930s, a mining team blasted the area and unknowingly exploded the lower legs of the skeleton. But the miners uncovered other fossils, and by late in the decade Sterkfontein was becoming a major source of material from A. africanus. One of the most famous is the partial skull called "Mrs. Ples" found a half-century ago and thought to be 2.6 million years old. Others, excavated in the 1960s and '70s, also proved to be 2.6 million years old. Clarke and colleagues found the bulk of the new skeleton – much of which is still embedded in rock – two geological levels below that.
Four years ago, Clarke's team discovered fragments of the hominid's apelike left foot and humanlike ankle, as well as a portion of its right shinbone. That find, dubbed "Little Foot," stirred hopes that more of the skeleton could be uncovered.
In 1997 Clarke was picking through a box of bones from Sterkfontein in a university storeroom when he noticed a hominid fragment that had been stored, erroneously, among monkey bones. He then found several more hominid fragments. Examination showed that they matched the Little Foot fossils.
He gave a cast of the right shinbone fragment to his two assistants, Stephen Motsumi and Nkwane Molefe, with instructions to renew the search of the grotto for matching fragments.
Two days later, after exploring the dank, dark grotto with hand-held lamps and hammers and chisels, Motsumi and Molefe found the fossil of a lower left leg and foot, plus a lower right leg. Side by side, the two legs were wedged between ancient rock layers. The fossil cast and the shinbone fragment were a perfect match. "I thought, 'My goodness, we must have the whole skeleton here,' " Clarke said.
Over the ensuing months, the team uncovered more of the skeleton, and last September they discovered the left side of the cranium. Chiseling delicately, they uncovered the cranium and the jaws, and then saw the glinting of the hominid's teeth. Little Foot was nearly complete.
The Geomagnetism Laboratory at the University of Liverpool in England dated the hominid at between 3.22 and 3.58 million years old based on magnetic characteristics of the surrounding breccia, or broken rock. That date would make it marginally older than "Lucy," discovered in Ethiopia in 1974, and one of the oldest known.
"Like the old song about the anklebone connected to the leg bone," said Tobias, "the whole thing fits together. This is the skeleton of Little Foot, which now we'll have to find a new name for."
Staff writer Curt Suplee in Washington contributed to this report.
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