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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). |