relatively picky eater who depended on extensive shrubland for food. In fact, most of the extinct megafauna were browsers of trees and shrubs rather than grazers. The authors speculate that humans disrupted the natural fire cycle by burning the landscape periodically. This, in turn, may have decreased the vegetation necessary for animals like Genyornis. The findings imply that even low-technology human impacts can have large-scale environmental effects.

More work is needed to prove that Genyornis disappeared at the same time-for the same reasons-as the rest of the extinct Australian megafauna. But recently Miller's group has begun to investigate sites that contain both Genyornis and other megafaunal fossils at what seems to have been the eve of their existence--younger deposits contain no trace of the extinct megafauna, only fossilized eggshells of the still-living emu. "We're starting to be able to put together a composite picture of the fossils in this age group," Miller said.

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Contact: Gabriel Paal
gpaal@aaas.org
202-326-6421
American Association for the Advancement of Science
7-Jan-1999

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