BLOOMINGTON, Ind. -- Scientists from Indiana University Bloomington and seven other institutions have unearthed skeletal fossils of a human ancestor believed to have lived about 4.5 million years ago. The fossils, described in this week's Nature (Jan. 20), will help scientists piece together the mysterious transformation of primitive chimp-like hominids into more human forms.

The fossils were retrieved from the Gona Study Area in northern Ethiopia, only one of two sites to yield fossil remains of Ardipithecus ramidus.

"A few windows are now opening in Africa to glance into the fossil evidence on the earliest hominids," said IUB paleoanthropologist Sileshi Semaw, who led the research.

Semaw and colleagues also report new evidence that suggests the human ancestors lived in close quarters with a menagerie of antelope, rhinos, monkeys, giraffes and hippos in a northern Ethiopia that was far wetter than it is today. The environmental reconstructions suggest a mosaic of habitats, from woodlands to grasslands. Research is continuing at Gona to determine which habitats A. ramidus preferred.

"We now have more than 30 fossils from at least nine individuals dated between 4.3 and 4.5 million years old," said Semaw, Gona Palaeoanthropological Research Project director and Stone Age Institute research scientist. The Stone Age Institute, a new research center dedicated to the study of early human evolution and culture, is affiliated with Indiana University's CRAFT, the Center for Research into the Anthropological Foundations of Technology.

In their letter to Nature, Semaw and his coauthors describe parts of one upper and two lower jaw bones -- with teeth still intact -- several loose teeth, part of a toe bone and intact finger bones. The scientists believe the fossils belong to nine individuals of the species A. ramidus. The scientists used argon isotope dating of volcanic materials found in the vicinity of the fossils to estimate their
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Contact: David Bricker
brickerd@indiana.edu
812-856-9035
Indiana University
19-Jan-2005

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