Complete Fossil

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Science  18 Dec 1998:
Vol. 282, Issue 5397, pp. 2183
DOI: 10.1126/science.282.5397.2183a

A nearly complete skeleton, including skull, of a 3.5-million-year-old apelike human ancestor has been discovered in the fossil-rich Sterkfontein caves in South Africa. It “might well be a new species,” says Ronald Clarke of the University of Witwatersrand in Johannesburg.

Clarke followed a trail of bones leading to the biggest prize, the first complete skull of an australopithecine, the genus thought to have given rise to early humans. In 1994, he spotted some hominid foot bones among a pile of Sterkfontein animal fossils (Science, 28 July 1995, p. 521). Then last year, Clarke happened upon some lower leg bone fragments, in a university storage locker, that fit with the foot bones. Convinced that the rest of the skeleton lay in the cave, he assigned two assistants to search in a large, dank area called Silberberg Grotto. The team eventually uncovered more bones and a skull, complete with jaw and teeth, still embedded in rock.

Clarke says the creature had humanlike heels but apelike big toes, suggesting it was at home both in trees and walking upright. With “massive” cheekbones and evidence for large jaw muscles, the skull doesn't appear to match known examples of the “gracile” variety of Australopithecus, A. africanus. The individual, about 120 centimeters tall, may be “an early form of A. africanus, or a southern form of afarensis”–the species made famous by “Lucy,” a 3-million-year-old skeleton found in Ethiopia. Paleomagnetic analysis of the surrounding rock has confirmed earlier dating and puts the bones at 3.22 million to 3.58 million years old. Clarke's report is in the current issue of the South African Journal of Science.

Paleoanthropologists are thrilled at the news. “What a wonderful thing to get complete fossils—it's what we all would love to find,” says Alan Walker of Pennsylvania State University in University Park. Walker points out that the skeleton can be used to address a host of questions relating to limb proportions, locomotion, the relationship of brain size and tooth size to body size, diet, and lifestyle. Clarke says it will take another year to complete excavation of the find.

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