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Re: dinosaurs and endothermy

In message <Pine.A32.3.91.950914140853.75058A-100000@holly.ACNS.ColoState.EDU>  
>      I was under the impression that crocodilian cannot expand thier 
> thoracic cavity to breathe but instead essentially diplace thier livers 
> to increase lung volume for inhalation.  Turtles use basically the 
> same method.  This is due to rigidity of thier torso caused by thier 
> armour.  Does this mean that dinosaurs could not expanfd thier thoracic 
> cavity either, but had to move drop thier livers as well?  There is no 
> evidence that the majorty of dinosaurs were very heavily armoured, so I find 
> it unlikely that they would have to adopt this peculiar and specialized 
> strategy.  If they didn't breathe like birds or crocodilians, how did they 
> breathe?

Despite the interest and all the discussion on dino breathing, remarkably little
has been written aboutit.  You might look at Hengst and Rigby's paper in the 
Dino Fest (1994 pp199-211) volume (person plug) for one version on this topic.  
AS Greg Paul has mentioned, several people have suggested the involvement of 
gastralia including a recent paper describing Apatosaurus yahnape. I suspect you
have been reading the Gans & Clark (1976) paper on Caiman breathing.  I believe 
they were referring to SUBMERGED animals where this adaptation to thoracic 
fixation makes sense.  Alligators & Caimans  do use SOME rib movment in 
terrestrial breathing, however.  It is far more complicated than one might 
think.  I expect to have a paper on this subject completed by Xmas assuming, of 
course, that the remaining experiments do not go sour (-saur??).  We are just 
concluding a lengthy and difficult study of crocodilian breathing mechanics and 
dinosaur breathing. I will be discussing the results at GSA this year for those 
of you attending there.  


Rich Hengst                         |                                        |
Biological Sciences Dept.           |                                        |
Purdue Univ. North Central          |                                        |
Westville, IN  46391                |                                        |  
(219) 785-5251                      |                                        |
                                    |                                        |
rhengst@centaur.cc.purduenc.edu     |                                        |