Re: From Science New, and more

["Tim Donovan" <msdonovan66@hotmail.com>]

> 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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