RE: Belly Ribs and Breathing

["Tracy L. Ford" <dino.hunter@home.com>]

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
Waylon Rowley
Sent: Tuesday, July 03, 2001 10:55 AM
To: dinosaur@usc.edu
Subject: Re: Belly Ribs and Breathing


David Marjanovic wrote:
> Uncinate processes are much more widespread (Willo
> the *Thescelosaurus* has
> huge uncinate plates).

Are you suggesting that ucinate processes are present
if not in an ossified form, then in a cartilaginous
form in all Dinosauria? Or is this simply a case of
convergent acquisition? If the latter is true, it has
no bearing, as there is usually only 1 or a few best
ways to solve an evolutionary problem.
    As for the role of gastralia in breathing....
I don't believe they were muscle powered (since some
dinosaurs fused them together) but rather flexible
bony rods with extensions of cartilage that simply
helped keep the ventral portion of the posterior air
sac (or whatever air sac filled that position in
theropods) open during inhalation. I wish I knew the
details of the contact between sets of gastralia; it
could be illuminating in this discussion.TTYL <<

Hmm...might as well chime in. I just did an article about gastralia for
Prehistoric Times. I won't go into details of it so you'll just have to buy
it :>.

Anyway, Leon Classens (The function of gastralia in theropod lung
ventilation at the A. Watson Armour III Symposium, The Paleobiology and
Phylogenetic of Large Theropods, also held at the Field Museum) showed that
yes, some gastralia are fused, some having a large flat area, the majority
of them have a 'sliding' hinge' allowing them to expand and contract during
breathing. They are paired and rod like. I believe others have said the same
thing. The Allosaurus at the USNM has broken gastralia which confused and
confounded Gilmore into thinking there are more than a pair (Dan Chure has
written this up).



Tracy L. Ford
P. O. Box 1171
Poway Ca  92074