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Re: Climate change



A.Gwin writes;

>The brachiosaurid can pick up and move hundreds of miles to
>the south (or north) to get to a warmer environment, but the little salamander
>has to stay there and freeze.

Yes, but a little salamander can also hibernate, and avoid the cold
weather altogether.  This could be an advantage if the entire
biosphere is drastically affected.

>But if you look at the fossil record, wherever there is a mass dinosaur
>extinction there is virtually no corresponding sharp drop in the number of
>small animal species.

Part of the impact hypothesis, is that the real end to the large
animal populations (including the sea reptiles) was caused by an
overall drop in food supply.  In this senario, a small animal would
actually have a *better* chance of surviving than its larger
contemporaries (simply because it needs less food to survive).

>With the information that I have now, my vote is for a global dino plague.

The major problem with the dino-plague idea is that most diseases are
species specific.  Only in very rare cases does a disease affect
animals that are distantly related, rabies being the only one that is
close.  Even so, rabies affects placental mammals primarily (with
only 70 my of evolution separating the groups), where dinosaur groups
had some 200 my of evolution separating the groups.  As a result, the
idea of a Late Cretaceous disease jumping across all dinosaur species
is highly improbable.

Rob

***
"Well, it's big and terrible."
        -GTKOM