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Re: Bigger dinosaurs had warmer blood.




--- "Richard W. Travsky" <rtravsky@uwyo.edu> wrote:

> > +++++++++++++++++++++++++++++++
> >
> > I'm thinking that this might have been the main
> > function of air sacs in dinosaurs (esp. large
> > theropods and sauropods).
> 
> In heat exchanger fashion? Are there any birds with
> air sacs that would also function that way?

++++++++++++++++++++++++++++++++++++

I believe that this is a feature of all birds. Birds
evaporate heat from their muscles and viscera into the
air sacs for quick dumping. Seeing as how birds lack
sweat glands, this is pretty much the only way that
they can keep cool. Lucky for them this way is far
more effective than the mammalian way.

For more see:

Bernstein, M.H. 1976. Ventilation and Respiratory
Evaporation in the Flying Crow, _Corvus ossifragus_.
Respiration Physiology. Vol. 26: 371-382.

Schmidt-Nielson, K.J.; Kanwisher, R.C.; Lasiewski,
J.E.; Bretz, Cohn & W.L. 1969. Temperature Regulation
and Respiration in the Ostrich. Condor. Vol. 71:
341-352.

Jason

"I am impressed by the fact that we know less about many modern [reptile] types 
than we do of many fossil groups." - Alfred S. Romer

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