Re: Ornithischian Lungs???

["Jaime A. Headden" <qilongia@yahoo.com>]

Kris Kripchak (MariusRomanus@aol.com) wrote:

<I've been trying to reach a conclusion as to what sort of lung Ornithischians
possessed. There's always so much attention paid to theropods and sauropods in
this regard. Everyone else is left out. I've seen Perry's argument about the
retroverted pubes supporting an abdominal wall muscle that vetilated the lungs,
but I was wondering what other ideas, if any, are out there. What I'm really
striving for are ideas on their aerobic capacities. So, any help whatsoever
would be much appreciated.>

  Well, if ornithischians used the form of pelvic aspiration that Carrier and
Farmer have suggested, with tight belly muscles and the possibility of
"uncinates" as in *Thescelosaurus*, NCSU specimen "Willo", we'd have a more
rigid ribcase and possible rigid lungs. However, I think because of the active
shoulder and quadrupedal larger ornithischians, a costal-driven breathing
system would work with locomotion to breathe. Then perhaps bipeds used a more
pelvic-driven breathing system versus costal in quadrupeds? I don't think
ornithischians had a rigid shoulder at all, and a mobile shoulder will distort
the chest cavity if the animals had a rigid ribcage as in birds, so it seems
unlilkely any ornithischian had a relatively "bird-like" lung.

  Cheers,

Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


                
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