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Re: Postorbital processes on jugals



----- Original Message -----
From: "Mickey_Mortimer11" <Mickey_Mortimer11@email.msn.com>
Sent: Monday, December 17, 2001 1:42 AM

> The description of Yanornis states "the jugal has a low ascending
process".

Where, if at all, can I get the PDF?

> 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).

Ah, that's the quadratojugal... Now I'd need something 3-dimensional to
guess whether the process is a neomorph to prevent the quadrate from too
much movement, sort of taking over the function of the tiny qj, or a genuine
postorbital process. The latter looks much less improbable to me now.

> Archaeopteryx also has a posteriorly placed ascending process.

No problem for me, heh heh. I still think it's rather far away from birds.

> I never
> mentioned one being present in Longipteryx,

In the Details On IIRC.

> though I assume it was.

As I wrote, there is something in the photo, but it's so big I rather think
it's a slightly displaced quadrate. Doesn't exactly rule out the presence of
the process, but may give the whole thing a question mark.

> Besides
> Confuciusornis, no other non-ornithurine pygostylians have well
> preserved/illustrated jugals.

:-(
Even *Sinornis*. Just checked.

> Protopteryx and Longipteryx may have well
> preserved jugals, but are not illustrated well enough to tell.

The photo of *P.* drives me crazy...

> So, assuming
> the following phylogeny is correct-

|-other coelurosaurs incl. Archie N
`-+-Shuvuuia Y
    `-+-Confuciusornis N
       `-+-Longipteryx ?
           `-+-Spanish nestling N?
               `-+-Yanornis N?
                   `-+-Hesperornis Y
                       `-Neornithes Y

the issue gets a bit more difficult. Well, probably I'd better use "absence
of contact between jugal and postorbital", which still has the primitive
state in confuciusornithids and is unknown in e. g. *Archaeopteryx*... Too
bad no skull is known for *Sapeornis*, which could decide the issue.