Until now, the oldest fossil skeleton of a human ancestor was the 3.2-million-year-old partial skeleton of Lucy, discovered in the Afar depression of Ethiopia, near Hadar, in 1974 and named Au. afarensis.
In 1992, however, while surveying a site elsewhere in the Afar, near the village of Aramis, 140 miles northeast of Addis Ababa, Middle Awash Project scientist Gen Suwa discovered a tooth from a more primitive creature more than 1 million years older than Lucy. After more fossils of the creature were found in the area from some 17 individuals, Suwa, White and project co-leader Berhane Asfaw published the discovery in the journal Nature in 1994.
Although that first paper initially conservatively placed the chimp-like creature in the Australopithecus genus with Lucy, the team subsequently created a new genus Ardipithecus for the hominid because of the fossils' significantly more primitive features.
After preparing their first report, the scientists continued to find more Ar. ramidus fossils in the Aramis area. A hand-bone discovered in 1994 by project scientist Yohannes Haile-Selassie, a paleontologist and curator at the Cleveland Museum of Natural History, eventually led the team to the partial skeleton now known as Ardi, which they excavated during three subsequent field seasons. The skeleton was disarticulated and scattered, and broken into smaller pieces: 125 fragments of skulls, teeth, arms, hands, the pelvis, legs and feet. In addition to this skeleton, the area yielded a total of 110 other catalogued specimens representing body parts of at least 36 other Ardipithecus individuals.
After the bones were excavated at the site, they were molded and painstakingly removed from their protective plaster jackets in the laboratory in Addis Ababa, where they were then photographed and reconstructed. Micro-CT scanners were used to study the inner and outer anatomy of the bones
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University of California - Berkeley