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Re: DINOSAUR digest 3384
Worth knowing. At least Solenodon phylogeny made it to
"Nature" so is quite reliable.
The phylogeny is reliable, but the calibration is not...
Yes, I think so. Large forest fires are unlikely to
cause extinction of dinosaurs.
They _alone_ are unlikely to have done that. But nobody claims that they
occured alone, without an impact winter, without acid rain, without a
postapocalyptic greenhouse, without a long-term perturbation of the water
cycle, and so on.
Second, in the scale of Earth, there had to be swamps,
seasonally unvegetated patches, areas of heavy
rainstorm and similar where forest fires couldnt
I guess this explains why anything survived...
Finally - one day after fire, plants begin to regrow
Maybe not if it's dark from all the soot, and certainly not if the rain has
negative pH values.
Of alternative theories:
These are _not_ alternatives. All of them _must_ have occured _together_,
based on what we know about big impacts and mathematics.
amphibians and freshwater
fish are very suspectible to acid rain.
True. Here the chemical composition of the soil and bedrock becomes
important -- limestone good, granite bad, for example. Perhaps this kind of
thing explains why Africa doesn't have *Neoceratodus* anymore, why gars are
today restricted to North America while the whole world seems to have had
them in the Late Cretaceous, why *Polypterus* became restricted to Africa,
why palaeobatrachids (aquatic pipoid frogs) are known from the Campanian
through early Pleistocene of Europe but only from the, IIRC, Maastrichtian
of North America, and similar freak patterns of biogeography.
Manmade acid rain was a catastrophe for freshwater fish in Scandinavia but
doesn't seem to have been noticed by alpine fish.
Small birds are very suspectible to smoke
(use of canaries in coal mines).
Is this about smoke? I thought it was about the gases that are sometimes
found in coal mines -- carbon dioxide, methane, funny sulfur compounds and
And indeed, there's no evidence that any bird below chicken size survived --
but the fossil record is so poor that this is negative evidence.
I agree there were large scale fires in K/T, but they
cannot explain extinction-survival pattern.
They alone can't, but they alone don't need to.