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Re: I wonder why....



Tried posting this yesterday, but for some reason it bounced back to me. (Obviously it didn`t reach the dinolist either).
 
----Original Message-----
From: Henri Rönkkö <overmind@iobox.fi>
To: saursThu@spool.iobox.fi <saursThu@spool.iobox.fi>; 27 Apr 2000
14:09:38.EET.DST@spool.iobox.fi <27 Apr 2000
14:09:38.EET.DST@spool.iobox.fi>
Date: Thursday, April 27, 2000 10:09 AM
Subject: I wonder why mammals and birds don't reach sizes characteristic of
greatest dinosaurs


>It has been proposed that the fast metabolism of these animals would create
too much heat. However, we do suppose dinosaurs were warm-blooded, don't we?


Hello,...I believe I made comment on this topic once before, and as I didn`t
recieve too much "flak"  from the group, perhaps my reasoning on the
subject was near the mark. I assume that the dinosaurian respiratory system
was very similar to that of the modern avian in that it allows for more
efficient flow of air basically by being a "flow through" type of system vs.
dead end  air sacs of mammals that only allow a "tidal" flow. (for more info
on this, and an excellant animation go to:
http://www.sci.sdsu.edu/multimedia/tracking/ )

I was once told that the avian system was a necessity not only for supplying
more air for the rapid avian metabolism, but to carry off  the excess heat
generated. Therefor, I concluded indirectly  that dinosaurs were capable of
getting so huge compared to mammals(...excepting whales) because they must
have possesed an avian type resp. system. (my humble opinion anyway).