University of California at Berkeley integrative biology professor Tim White, co-director of the project, called it "the most detailed snapshot we have of one of the earliest hominids and of what Africa was like 4.4 million years ago."
The first Ardipithecus ramidus bone, a tooth, was found in the Afar desert region of Ethiopia in 1992. The find was made 18 years after the 3.2 million-year-old partial skeleton of Lucy, known as Australopithecus afarensis and previously the earliest known hominid, was discovered in a different part of the same region.
In 1994, the first bone of the now rebuilt skeleton, nicknamed Ardi, was located. Since then, 125 other bone fragments of the skeleton were recovered.
The reconstruction now shows a 4-foot-tall creature believed to have walked upright for short distances and able to carry objects while walking, but which still lived primarily in the trees.
Ardi probably weighed about 110 pounds, had a small face and a brain about the size of a chimpanzee, one-fifth the size of a human brain, according to White.
CT scans of Ardi's tooth enamel revealed the creature was an omnivore. The team believes Ardipithecus searched the ground for plants, mushrooms, invertebrates and possibly small vertebrates.
Ardipithecus ramidus represents the first known hominid to have arisen since the hominid line that evolved into humans split 6 million years ago from the line that led to chimpanzees, our closing living relatives.
The comparative differences with the Lucy skeleton, which was better adapted for walking on the ground, suggest that "hominids became fundamentally terrestrial only at the Australopithecus stage of evolution," White said.
The group's findings are detailed in the Oct. 2 issue of the journal Science.