A publication of the Archaeological Institute of America
A nearly complete 1.4 million-year-old skull of Australopithecus boisei has been found at Konso in southern Ethiopia by a team of paleoanthropologists led by Gen Suwa of Tokyo University and Yonas Beyene of C.R.C.C.H. of Ethiopia. Known as KGA10-525, the new specimen is the first to be found with both jaw and cranium. With a capacity of 545 cubic centimeters, it is the largest A. boisei cranium ever found, almost certainly that of a large male who was of a relatively advanced age when he died.
A. boisei belongs to an extinct group on a branch of the hominid tree that split from the modern human line between 2.8 and 3 million years ago. It had a massive skull and broad, concave face with prominent flaring cheekbones, a large jaw with thickly enameled molars three times the size of our own, massive chewing muscles, and a relatively small cranium. More than 100 specimens have been found in Kenya, Tanzania, and Ethiopia, nearly all dating from between 2.3 and 1.6 million years ago.
The new skull was found between younger volcanic tuffs, dating from between 1.43 and 1.41 million years ago. "While we have never found A. boisei so recent in time, so complete, and at a location so far north," says team member Tim D. White of the University of California, Berkeley, "the most important aspect of this find is that the new skull exhibits many features previously assigned to several other australopithecines." The bony crest atop its head, for example, is far more pronounced at the back of the skull than at the front, a trait common in A. aethiopicus.
According to Suwa, KGA10-525 bears some distinctive boisei traits, including features of its dentition, but lacks some of the species' diagnostic features, such as protruding cheekbones. "Over the past five to ten years, paleoanthropologists have gotten carried away with naming a new species every time they find a fossil with a slightly different morphology," says White. "What the Konso find has confirmed is that there was considerable morphological variation within the species in East Africa, more than previously thought."
In addition to KGA10-525, Suwa and his team found the remains of at least eight other A. boisei in the same fossil bed, which four years ago yielded remains of H. erectus and one of the richest and oldest assemblages of hand axes ever found. The new finds point to the coexistence of A. boisei and H. erectus. "Whether the two saw each other on a daily basis or had any sort of interaction, we have no idea," says White.