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Re: From Science New, and more




On Sun, 10 Nov 2002, John Bois wrote:

I only meant to say that the study of dinosaurs is appropriate
(for all we know) for the the study of dinosaur's extinction

Right. Note the loss of some diversity about 2 million years before the end, which suggests another factor causing a preliminary extinction.



--this is true
whether or not some massive force hit.  For example, what was it about the
dinosaurs that made them susceptible and not other living things?

You mean many other living things. Dinosaurs were supposedly more vulnerable because of their prodigous food requirements at a time of energy depletion. Recent research, however, casts doubt on the impact scenario. The initial proliferation of ferns while the dust was settling rules out freezing temperatures and darkness. (N.C. Arens, pers. comm.)Modern analogs of the K-T fern species, including a tree fern, require full sun to make spores, which are present in the upper impact layer.


Ordinarily the replacement of angiosperms and conifers with ferns would probably doom the dinosaurs since ferns aren't energetically rewarding. Tree ferns requiring full sun may well have been different. In any event recent research suggests only 10-20% of the biomass burned, which implies widespread survival of "good" vegetation in the absence of an impact winter.



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