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Re: dinosaurs and endothermy



In message <Pine.A32.3.91.950914140853.75058A-100000@holly.ACNS.ColoState.EDU>  
writes:
>      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?
> 
> J.MARTZ 

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




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