Re: Postorbital processes on jugals

["Mickey_Mortimer11" <Mickey_Mortimer11@email.msn.com>]

David Marjanovic wrote-

> I'm checking the distribution of absent postorbital processes around the
> origin of birds and have come across more confusion than just the absence
in
> mononykines and the presence in confuciusornithids: HP Mickey Mortimer has
> said onlist that basal Ornithothoraces still have the processes and has
> mentioned the Spanish nestling, *Longipteryx* and *Yanornis*. Are there
> others? The photo available of *Yanornis*
> http://www.scichina.com/kz/0105/kzfm05.stm isn't detailed enough for me to
> tell; does the paper get more specific? The photo of *Longipteryx*
> http://www.scichina.com/ky/0111/kyfm11.stm is almost detailed enough and
> seems to show one, but is that maybe a disarticulated quadrate? The paper
on
> the Spanish nestling explicitely speaks of a "jugal bar", labels no
> postorbital process on it, and the quadrate in the photos (especially that
> of the counterslab, Fig. 2) looks a lot like the feature in *Longipteryx*.
> Both the photo of the main slab (Fig. 1) and the reconstruction drawings
> (Fig. 3) do show an ascending process on the jugal, but it is far caudal,
> lateral to the quadrate, so that I think it is the fused quadratojugal.
How
> far off am I with these interpretations? Are there other ornithothoracines
> except confuciusornithids with postorbital processes on the jugals? Please
> respond soon, I need it, as I'm writing an update to my paper, and I'll
> claim that interpreting the absence of said processes in mononykines and
> {Ornithothoraces > Confuciusornithidae} as a synapomorphy reversed in C.
is
> still as parsimonious as assuming convergence if nobody stops me :-)

The description of Yanornis states "the jugal has a low ascending process".
The dorsal process of the Spanish nestling is placed far posterior, and is
not a fused quadratojugal (which is small and preserved separately behind
the jugal in figure 3A, notice it is articulated in the reconstruction).
Archaeopteryx also has a posteriorly placed ascending process.  I never
mentioned one being present in Longipteryx, though I assume it was.  Besides
Confuciusornis, no other non-ornithurine pygostylians have well
preserved/illustrated jugals.  Protopteryx and Longipteryx may have well
preserved jugals, but are not illustrated well enough to tell.  So, assuming
the following phylogeny is correct-
|-other coelurosaurs N
`-+-Shuvuuia Y
  `-+-Archaeopteryx N
    `-+-Confuciusornis N
      `-+-Longipteryx N
        `-+-Spanish nestling N
          `-+-Yanornis N
            `-+-Hesperornis Y
              `-Neornithes Y
It would be extremely unparsimonious to use it as a metornithine
synapomorphy and inappropriate to use it as a pygostylian synapomorphy.
Seems like a good ornithurine synapomorphy to me.

Mickey Mortimer