Re: DINOSAUR digest 3384

[David Marjanovic <david.marjanovic@gmx.at>]

> 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
> spread.

I guess this explains why anything survived...

> Finally - one day after fire, plants begin to regrow
> providing food.

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 
the like.

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.