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Re: surface/volume ratio and water loss in smallest amniotes
On Thu, Feb 11th, 2010 at 2:54 AM, David Peters <email@example.com> wrote:
> Question is: Whether or not the smallest pterosaurs were adults or
> hatchlings, if they were in the airstream, were they evaporating at a
> dangerous rate?
Maybe if they had highly permeable skin like that of amphibians, or even porous
with sweat glands like some mammals. Having membaneous wings would probably
need to sweat to keep cool though.
Perhaps the apparent lower size limit for flying vertebrates has more to do
with heat retention than
evaporation? Small creatures with wings might be more prone to heat loss in
cool conditions, if
having wings drastically increases their surface area to volume ratio (which I
suspect would be the
case - especially with membraneous wings). All flying vertebrates appear to
endotherms, if pterosaur integument is anything to go by, so avoiding
catastrophic heat loss might
be a limiting factor for minimum size.
GIS Specialist Australian Dinosaurs
Melbourne, Australia http://home.alphalink.com.au/~dannj