 April 12, 2005Fossils of Apelike Creature Still Stir Lineage Debate
The discoverers described the fossils as belonging to the earliest known humanlike primate, or hominid. They named the new species Sahelanthropus tchadensis and commonly call it Toumai, meaning "hope of life" in the local language of Chad. But several other researchers disputed the interpretation, contending that the skull was too apelike to be a hominid. So the discoverers went back to Chad and found additional evidence, particularly two jawbones and an upper premolar tooth, that they say confirms their original conclusion. Another science group has produced a computer-generated reconstruction of what Toumai looked like. In a report in the current issue of the journal Nature, Dr. Michel Brunet of the University of Poitiers in France and his colleagues said the new fossils established critical differences between Toumai and African apes, features consistent with a species "close to the last common ancestor of chimpanzees and humans." The size of Toumai's brain and the shape of its skull were similar to a chimp's, but its face, teeth and brow ridge were more like a hominid's. Another group, led by Dr. Christoph P. E. Zollikofer of the University of Zurich, said the reconstruction of the badly damaged and fragmented skull confirmed that Toumai "is a hominid and is not more closely related to the African great apes." In a separate report in Nature, Dr. Zollikofer's team said the fossils and the three-dimensional reconstruction indicated that Toumai might have walked upright. One of the skeptics, Dr. Martin Pickford of the National Museum of Natural History in Paris, has not changed his mind. "What we're saying is that it is an apelike animal," he told the BBC. "It may well have given rise to bipedal hominids, but it's not yet a bipedal hominid." Other scientists said the new research, particularly the digital restoration of the skull, strengthened Toumai's hominid credentials. Dr. Ian Tattersall, a paleoanthropologist at the American Museum of Natural History, said the poor condition of the fossils would continue to raise questions about the new species. He said he supported the hominid status for Toumai but was "eager to make further finds in Chad, perhaps something in better condition." |
This reconstructed skull was thought to belong to the earliest known humanlike primate. But some researchers said the skull was too apelike to be a hominid.
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