Re: Belly Ribs and Breathing

[Waylon Rowley <whte_rbt_obj@yahoo.com>]

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

-Waylon

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