Re: Crocs, Amphibians, Small dinosaurs and the Impact theory.

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

Now that it seems like Listproc doesn't like French university servers, but 
has nothing against Austrian ones...

> I've heard Bakker use the fact that amphibians are the
> most sensitive to climate change to argue against the
> Impact Theory and in favor of disease.

Some seem to be sensitive, others not...

> What about in
> the Permian-Triassic extinction event? Does he favor
> disease there too?

Has he ever talked about that one...?

> Moving to the other side. I admit that frogs are very
> sensitive animals.

The wood frog, *Rana sylvatica* (North America all the way to the Arctic 
Circle), simply freezes in winter. Half of the body water freezes, and each 
cell, filled with glucose and urea to prevent freezing, survives the winter 
on its own. Of course this is a quite extreme example, but in the light of 
desert frogs, for example, I wouldn't say that frogs in general are "very 
sensitive animals".

> So if the Permian-Triassic
> extinction was caused by a massive drought and
> increasing temperature

What's the evidence for a drought? AFAIK there is only evidence for the 
large-scale disappearance of vegetation, which may have been caused by 
drought or (more probably) something else.

> In WWM the labyrinthodont "cocooned" itself (in what
> exactly?) in an attempt to wait out the drought. Do
> amphibians do this?

A few do http://tolweb.org/tree?group=Sirenidae&contgroup=Caudata, and so do 
lungfish (with self-made slime). But keep in mind that today's amphibians 
are more closely related to us than to any "labyrinthodont".

> The same question for Crocodiles as well. If they
> cannot tolerate colder climates (which is why
> labyrinthodonts survived for extended periods in
> colder areas?) how can they tolerate the sun being
> blocked out?

The Mississippi alligator does tolerate freezing... just not too much.

Crocodiles and temnospondyls seemingly coexisted happily throughout the 
Jurassic, so I don't see why they should have competed.

> it says that the since only fern species were dominant
> after the K-T boundary all the herbivorous dinosaurs
> including the small "polar dinosaurs" died out. How is
> this evidence as to why the "polar dinosaurs" died out
> if they were more adapted to the cold and (as far as I
> know) weren't ferns an adequate food source for the
> small herbivores?

I'd simply say it is not evidence. We don't know who liked ferns and who 
didn't.