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Re: [saola]; pneumatic bones



David Marjanovic wrote-

> BTW, as I'm reading Supplement 1 of Dinosaurs: The Encyclopedia and
various
> SVP meeting abstracts, it turns out that my argument that oviraptorosaurs
> and birds share pneumatic sacral and caudal vertebrae suffers from a few
> complications -- carcharodontosaurids/-ines have pneumatic tails, too, as
> allegedly do tyrannosaurs, and *Archaeopteryx* has a small pneumatic
opening
> in the pubis. The Supplement 1 article on *Nedcolbertia* also implies that
> ornithomimosaurs, troodontids and tyrannosaurs have some special type of
> vertebral pneumaticity; can someone enlighten me on this?

I've never heard of pneumatic caudal vertebrae in tyrannosaurids.  What is
the reference?  The presence of caudal pleurocoels in carcharodontosaurids
does not complicate the oviraptorosaur-pygostylia hypothesis, as they are
too far removed from either group to affect parsimony.  Two obvious ways to
cast doubt on the theory would be to show basal members of either group
lacked the character, or show it was present in a competing sister group to
pygostylians as well.
The quote in Glut's supplement that you are referring to is, "having simple
pneumatic dorsal vertebrae unlike ornithomimids, troodontids and
tyrannosaurids".  This is from the original description's diagnosis.  The
only other reference to dorsal vertebrae in the description is, "The few
dorsal vertebral fragments from CEUM 5072 show little beyond that the dorsal
vertebrae were pneumatic, with simple large air sacs".  Ornithomimids and
troodontids lack dorsal pleurocoels, so the comparison makes sense in that
way.  However, I think tyrannosaurids have pleurocoels on most, if not all,
dorsals; in which way the quote is confusing.  Perhaps Kirkland is reading
and has an explanation....

Mickey Mortimer