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Re: Warm Blooded vs. Cold Blooded



At 8:04 PM 9/11/95, Bobette Ray Dickerson wrote:
>On Mon, 11 Sep 1995, GREGORY LEE SMITH wrote:
>
>> I would like to address the issue of "Were dinosaurs warm or cold blooded?"
>> I think they were warm blooded.  They weren't built like today's
>> reptiles, they were built like mammals.  To me, the herbivores were like
>> todays elephants, cattle, and deer.  They spent their days grazing and
>> avoiding getting eaten by the carnosaurs who were like todays lions and
>> wolves.  Being cold blooded would have made it very difficult for
>> dinosaurs to exist because of their size.  By the time they were warmed
>> up enough to move it would have been getting dark again.
>>
>Robert Bakker has several papers out that address this subject.  Not to
>mention his book, The Dinosaur Heresies.
>
>I think that the whole idea of dinosaurs as cold blooded animals is out
>dated and can't stand up under any kind of scrutiny.
>
>
>Bobette Dickerson
>Department of Biology
>University of Nevada Reno


        And now to be flamed:  As much as I hate to admit it, John Reuben
has raised several valid points against truely endothermic dinosaurs.  And
as far as not holding up to scrutiny, Bakker's book falls like a house of
cards upon any close examination.  There is abundant evidence to support
the notion that the basal metabolic rates of dinosaurs ran at a much higher
tempo than the rates of lepidosaurs.  There is NO EVIDENCE to support the
notion of ENDOTHERMY (as thermogenesis from series of metabolic pathways
that generate heat via oxidation of food and/or fat) in dinosaurs.  Bring
forth bone histology,  functional morphology, etc., and they'll all
indicate the same thing:  Dinosaurs seemed to have possessed the potential
for prolonged aerobic activity.  Does this indicate true endothermy? Nope.
Until we can run a blood work-up on the big, dead guys, we can't say
endothermy.  I figure this message will have folks flaming bloody murder,
we'll see......

 From a former Bakkerite who has since taken a few courses in animal
physiology and biochemistry.



Jason J. Head
V.P. graduate student
Dept. of Geological Sciences
Southern Methodist University
Dallas, Tx. 75275