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Oviraptor Palatines



David Marjanovic (David.Marjanovic@gmx.at) wrote:

<Let me guess -- radiale, intermedium, ulnare, semilunate,
distal carpal 3?>

  Two proximal, three distal; the intermedium may be lost.
Ulnare and radiale, distal carpals 1 - 3. The semilunate can
form from either distal carpal 1, or from a union of distal
carpals 1 + 2.

  Mickey Mortimer wrote:
 
<<Deinonychosaurs are still the sister group of Yandangornis +
Pygostylia however. Elzanowski never mentions the triradiate
palatine of Archaeopteryx, though I should note that
oviraptorids have this character too. As caenagnathids lack it,
it was probably due to convergence.>>

<=8-) So triradiate palatines can evolve by convergence. --
Interesting that Elzanowski doesn't mention it, because his &
Wellnhofer's JVP paper on the seventh specimen of
*Archaeopteryx* (March 1997, I think) explicitely says *A.* is a
bird because of its triradiate palatine...>

  And may still be correct. The triradiate palatine in
_oviraptorids_ is possibly convergent, as Mickey says [well,
okay, he say "probably" :)], but this does not say much for
*Archaeopteryx.* The morphology of the ectopterygoid in the
oviraptorid palate is unique; it shares the loss of the
external, jugal process with segnosaurs, and is longer than wide
as a result. However, the ectopterygoid is turned about 45
degrees to the sagittal plane, so it is diagonal in section, and
this shows up in a very strange way to which I shall not -- now
-- get into detail. You will have to wait for this. Several
anatomical features of the bone make this rather incomparable to
anything else with a ectopterygoid except birds and segnosaurs,
and caenagnathids (which actually don't differ that much). The
mophology of the ectopterygoid does not look to be very
comparable to birds or other taxa to make this a detirminate
character in diagnosing its position, as I see it. The palate in
oviraptorosaurs has been doing some pretty funky evolution that
needs to be unraveled, because there's just one group that had
anything like it -- dicynodonts -- and guess what? They're also extinct.

=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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