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Re: pneumatic bones



----- Original Message -----
From: "Mickey_Mortimer" <Mickey_Mortimer11@email.msn.com>
To: <dinosaur@usc.edu>
Sent: Friday, March 02, 2001 7:00 AM
Subject: 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?

Have yet to find it (suffering from selective memory); it must be an SVP
meeting abstract from 1998, 1999 or (improbably) 2000.

> 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.

Sure; it constitutes a "precedence case" that shows that caudal pleurocoels
evolved more than once.

> 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.

Is there any such evidence?

> 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".

Ah! Long live primary literature!

> 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.

Pneumaticity in all dorsals also occurs in *Torvosaurus* and *Sinraptor*, I
remember to have read (probably in the same abstract as above :-( ), whereas
*Allosaurus* has only 4 pneumatic dorsals (I don't know whether they were
speaking of any pneumatic features or only of true pleurocoels).

BTW, Dinosaurs: The Encyclopedia Supplement 1 consistently uses Manuraptora
and Manuraptoriformes instead of -i-, citing a paper by Charig and Milner
1997 where it was pointed out that the i is etymologically totally incorrect
(I can confirm this). Are there any reasons not to adopt this emendation?