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Tough to infer an asteroid from paleontological data. I think we should get out of that business since the fossil evidence does not say anything about an impact. It can only tell us something about the environmental conditions, before and after an extinction event, and perhaps the timing. The evidence comes from geochemistry, mineralogy, geologic mapping, and such things that would record an impact. Now that does not mean that we don't have much to contribute, for example by defining closely the pre and post evironments, we could then ask our physical/chemical colleagues to get us from one to another with their scenario, which usually causes them all kinds of trouble. But if we argue about impacts from fossil evidence alone, we degrade our own positions because our data do not speak to impacts. Jere >If the extinction of dinosaurs, etal, is due to an impact induced imbalance in >the late Cretaceous environment, then the events took place during a shorter ti >me interval than the resolution of stratigraphy. The evidence can only be coinc >idental. There has to be "reasonable guilt." For some what is reasonable is wha >t is popular! What would be an "absolute proof?"I don't know! > Gil Brenner Jere H. Lipps, Director Museum of Paleontology University of California Berkeley, California 94720 USA Voice: 510-642-9006. Fax: 510-642-1822 Internet: jlipps@ucmp1.berkeley.edu
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