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题目材料：
Archaeologists in Australia have never found sites where large extinct animals were killed, and it seems likely that many species of megafauna had become extinct prior to the arrival of humans. This might mean that there was minimal coexistence between humans and megafauna; yet there are sites that may well display temporal overlap, such as Cuddie Springs. If humans exploited megafauna, then why are there no kill sites? While Flannery (1990) argued that the rapid speed of the extermination may be responsible, it is more likely that lack of preservation of material dating to more than 40,000 years ago is responsible. Nevertheless, environmental signatures consistently point to the reduction in range and density of large animals, if not their final extinction, between 40,000 and 50,000 years ago, coincident with the arrival of people, and so the appearance of human hunters in the landscape is implicated in the extinction process. The timing of extinction trends in these mega- animals coincides with intensification of long-term continental drying, reductions in resource levels, and restructuring of the environment, and so even low levels of predation by the new human hunters may have tipped some species into terminal declines or accelerated declines already underway. Most likely it was not intensive or exclusive hunting of these large animals that reduced their populations perilously, but merely the addition of a new social carnivore to stressful ecological circumstances.
以上解析由 考满分老师提供。
