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Re: CNN:Is it snowing in Oregon?



Endothermy simply means majority of body heat is generated internally,
ectothermy the opposite. Animals with the ability to sustain high levels of
aerobic activity would generate so much heat from muscular and supporting
organ work that they would be endotherms with elevated energy budgets. Using
feathers to retain body heat a substantial degree of homeothermy could be
sustained. This is true even if resting metabolism is as low as in reptiles. 

I agree that aerobic exercise capacity in dinosuars was elevated above
reptilian levels, strongly in most. A major problem with the Ruben et al.
hypothesis is that it is speculative and questionable in that may not be
possible for vertebrates - because of issues involving their centralized
respiro-circulatory system - to have a strongly elevated aerobic exercise
capacity with out also having an elevated resting metabolism. Indeed, it is
ironic that Ruben is effectively abandoning the aerobic capacity hypothesis he
coauthored which argued for a link between exercise and resting metabolic
rates. 

Among dinosaurs, only ornithopods with their mammalian lumbar region show
evidence for elevated aerobic capacity via a mammal-like diaphragm.
Saurischians were using air-sacs alone to ventilate high aerobic exercise
capacity. Pterosaurs probably had both. 

GSPaul