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Re: nice cover painting - Re: NEW BOOK: Dinosaurs of Eastern Iberia

Thanks for the data! Now I wonder if even dog mouth breathing is not
just a consequence of panting instead of increase in oxygen uptaking
during chases. What I understand from your points is that mouth
breathing is just consequence of panting in reptiles, including birds.

However, I think that observing that aerobic exercise above normal
levels does not require opening the mouth, as you indicate for birds
and other reptiles, does not imply that the reptiles will not open the
mouths to breathe when the aerobic exercise is even higher than some
maximal capacity breathing only through the nares can permit.

However, as strenuous aerobic exercise would generate much heat, the
usefulness of mouth breathing will be difficult to test because mouth
opening can be the result of overheating instead (some careful
experiment lowering environmental temperature as the temperature of
the animal increases may be required).

2011/10/20 Jura <pristichampsus@yahoo.com>:
> Reliance on anaerobiosis (which is an excuse that I feel is used far too 
> often for reptiles) shouldn't matter for this. If a reptile is going at an 
> aerobically sustainable speed, or slightly over it, they still keep their 
> mouths shut when breathing. Even if they were running anaerobically, there is 
> still a lack of mouth breathing during the oxygen recovery phase.
> As for birds, I'd recommend checking out Michaeli and Pinshow 2001. In an 
> attempt to measure total water loss in pigeons, they tested pigeons in flight 
> for an hour, at a time. The pigeons were trained to carry weights that 
> constituted 3% of their total mas during the flight. Despite a 10-16x 
> increase in breathing frequency, the birds were never observed to have used 
> their mouths. In fact the only time the authors noticed the birds mouth 
> breathing, was when the ambient temperature was starting to exceed their 
> thermoneutral zone (the birds started panting). Incidentally, that is also 
> the time that one typically sees other reptiles mouth breathing too.
> Jason
> Ref:
> Michaeli, G., Pinshow, B. 2001.Respiratory Water Loss in Free-Flying Pigeons. 
> J.Exp.Biol. Vol.204:3803-3814.