Re: _Discover_ article

[Nick Longrich <longrich@stardot.com>]

On Mon, 25 Nov 1996, Stephen Faust wrote:

> On Sun, 24 Nov 1996, Dave L. Hardenbrook wrote:
> 
> > Has anyone seen the article in the December _Discover_ magazine
> > about Tomasz Owerkowicz using nasal cavities as refutation of
> > hot-blooded dinos and confimation of the mass homeothermy theory?
> > He says that dinosaurs lacked turbinates, special organs in the
> > nasal cavity of warm-blooded animals.  He also thinks that the nasal
> > cavities themselves were too small to allow dinosaurs to inhale a
> > sufficient quantity of oxygen to sustain a warm-blooded animal.
> > Anyone care to comment on this thesis?
> 
> You might want to email your thoughts and speculations re:hot vs cold - 
> blooded dinos to Hillenius at the College of Charleston, SC.Thats 
> hilleniusw@cofc.edu.I have read the article and studied under him.He 
> found that dinosaurs studied, including several therapods, had neither 
> turbinates or projections within the nasal cavity that might have 
> supported turbinates.The nasal cavities of dinosaurs studied were 
> similar to those of crocodiles, narrow and much smaller than cavities 
> seen in endotherms.
> Tomasz found that stress produced changes in reptilian bone that would 
> lead one to conclude the bone came from an endotherm.
> Reptilian physiology would not have precluded the level of activity 
> depicted in "Jurrasic Park". The only inaccuracy in the film: dinobreath 
> would not have misted refrigerator glass.

        Before GSP goes and growls at us all...
GSP did a poster at the SVP on the RTs (acronymania...) showing how the 
relatively large  size of  the heads of many dinosaurs makes the nasal 
passages look smaller.  I think  the drawing showed that the nasal passages 
of a mid-sized theropod  were  about the same size as those of a similarly 
sized elephant-bird.  Relative to the skull, of course, the nasal passages 
of a pinheaded elephant bird  were *much* larger than those of a big-headed 
theropod.
        Also, GSP notes that they may have been cartilagenous in many cases 
and so would not show up. Bone textures also seem to be far more 
complex and difficult to read than anyone had thought they would be.
        Finally, a full-body insulatory coat on the theropod Sinosauropteryx 
is very good evidence that it was fully endothermic (endothermy 
naturally being a diverse range of physiologies encompassing extremes 
such as the lukewarm monotremes and the hot-blooded songbirds) and it is 
simplest just to assume that this animal was warm-blooded. This, and the 
fact that close dinosaurian relatives, the pterosaurs also appear to have 
had insulation, further supports the possibility that dinosaurs as a 
group may have been endotherms. Brooding behavior in oviraptor, high 
degrees of aerobic activity, presence at very high latitudes, and high 
growth rates are further substantiating evidence of endothermy in the 
dinosaurs.