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Re: Archie skull pneumatics?



Nick Gardner (ratites637@hotmail.com) wrote:

<The elongated prenarial premaxilla is present in "enigmosaurs" (as David
noted), spinosaurids (Sereno et al. 1998; Sues et al. 2002), and avians. I
never really understood this character but I assume it could be related to
 dietary functions? Help... please.>

  There is no real elongated prenarial premaxilla in either
oviraptorosaurs or *Erlikosaurus*; in nearly all taxa, the external naris
progresses to the rostral end of the premaxilla and is even closer to the
edge than it is in *Velociraptor*.

<I was under the impression that *A.* did not have an incomplete
postorbital bar. I know that *Shuvuuia* does not (Suzuki et al. 2002), and
that the contact between the postorbital and jugal is weak in
*Bambiraptor* (Burnham et al. 2000).>

  Both *Archaeopteryx* and *Bambiraptor* have incomplete preservation of
the postorbital bar.

<How many non-avian theropods lack dental serrations anyway?  I can only 
think of *Caudipteryx*, *Byronosaurus*, *Compsognathus*, and juvenile
tyrannosaurids.  I'm sure there must be more, but I can't think of them
all. I thought that perhaps *Scansoriopteryx*, *Microraptor*,
coelophysids, *Dilophosaurus*, and *Shuvuuia* might, but I can't be sure.>

  They are absent in some tyrannosaur teeth, *Pelecanimimus*, *Shuvuuia*,
*Mononykus*, *Byronosaurus*, premaxillary teeth in *Sinosauropteryx* and
*Compsognathus*, *Caudipteryx*, *Incisivosaurus*, *Epidendrosaurus* (not
known in *Scansoriopteryx*), and perhaps some teeth in coelophysids. In
*Protarchaeopteryx* there are crenellated edge of the carinae, but I do
not think these qualify as serrations as slots do not appear to exist in
the carinae themselves. All "dromaeosauroids" have serrations, as does
*Sinovenator*.

<As for basal constriction of the teeth in non-avian theropods, I know it
is present in *Caudipteryx*, *Microraptor*, *Shuvuuia*, segnosaurs, 
troodontids, and perhaps *Protarchaeopteryx*?>

  *Caudipteryx* does not have a basal constriction, and
*Protarchaeopteryx* has them in the premaxillary teeth anyway. They also
exist in *Pelecanimimus*, *Sinosauropteryx*, *Compsognathus*, *Eoraptor*,
etc.. 

<There are other non-pygostylian theropods with very short tails, such as
the avian *Jeholornis* (22), the curious *Protarchaeopteryx* (23), and
*Caudipteryx* (22).>

  Actually, *Caudipteryx* has 24.

  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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