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Re:warm-blooded



Re: Warm-blooded
On Thu, 10 Jul 1997  Dinogeorge writes:
>Did you >directly< measure their body temperatures? That's the ONLY
>acceptable >evidence.
   We can not take the pulse of a dinosaur either but we believe they
lived.
A jury can send a man to death but it never actually sees the crime.  What
we believe is fact is based on the preponderance of the evidence and is
only
as good as the evidence.
   The only facts in paleontology are what was found and where.  The rest
is just theories trying to make the best fit with the information we know
at
the time.  The question is which theories fit the evidence better.
Therefore,
I usually get upset when someone says that the only possibility for ...
was...
I prefer someone saying ?Many paleontologists...?  or  ?My  theory is
...?.
   A better question than were dinosaurs endothermic or warm-blooded is
?Were the dinosaurs energetic like modern birds and mammals?.
   I think the evidence supports active energetic dinosaurs.  Dinosaurs
apparently dominated the landscape over energetic mammals for over 150
million years.  Some appeared to live in vast herds, presumably moving
over large areas.  Some appeared to grow quite rapidly.   Others achieved
large sizes.  Some even descended into birds.
   The facts show that at least twice, endothermy developed in diverse
animals.
Why did dinosaurs surpass other similar bipedal thecodonts, leaving only
the
crocodillians in the cold-blooded predator niches?  How did pterosaurs get
the
energy to develop flight?  When did the bird lung and four chamber heart
allow
the development of endothermy?  One explanation that could combine all
these
thoughts is that endothermy developed in the bird/dinosaur/pterosaur
ancestors
and allowed active lifestyles to develop.
   In summary, you could say that many paleontologist believe that some or
all
dinosaurs had metabolisms and activity levels similar to birds and
mammals.
However, not everyone is in agreement, especially on how, when, or where
endothermy developed.
>Everything< else is supposition, >hypothesis, speculation.
   That is the fun part of paleontology, speculating about how the
dinosaurs
or other animals lived and how they might have evolved, then seeing if the
evidence shoots you down or not.
                Mark Shelly