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



> 2011/10/19 Jura <pristichampsus@yahoo.com>:

>>  As elitist as this is going to sound, "mouth breathing" is a 
> distinctly mammalian thing. Reptiles and birds both breathe almost entirely 
> through the nose, even when they are going full out.
> 
> Sounds logical. For lizards and crocs mostly rely on anaerobiosis,
> while birds may have such an efficient mechanism of O2 uptake that
> they may not need to increase it by mouth-breathing. However, I do not
> know if birds ever have to rely in mouth breathing during aerial
> chases (as either prey or predators), which would better compare with
> the moments in which we mammals need to take some extra O2, above our
> common sustained aerobic capacity (I suppose filming bird aerial
> chases in such a detail in these cases would be very difficult).

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

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.