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Re: dinosaur@usc.edu



David Marjanovic wrote-

> Elzanowski & Wellnhofer (1996) has 3 figures that show that bone. In fig.
1
> it looks L-shaped. I only have a bad copy of fig. 4 (a photo), I'll have
to
> look at the original. In fig. 7B the caudal process is bigger than the
> squamosal one, so it's anyway not L-shaped in that figure. Fig. 12 is a
bit
> confusing. On the whole the qj has almost the same shape there as in fig.
1,
> but if the jugal and the squamosal process are labeled correctly, then the
> 3rd process points ventrally and not caudally. Hm. The text is silent.
>         The only difference between the qj in fig. 7B above and the
> reconstruction of *Sinornithosaurus* in Xu & Wu (2001), fig. 3A, is that
in
> the latter the postorbital process does not look broken off and that the
> jugal process isn't that long. The bulbous caudal processes look IMHO very
> similar.
>         So can I on the whole conclude that *Archaeopteryx* has an
incipient
> version of the feature, while pygostylians don't? :-)

Figures 1 and 4 are of the same bone that's ullustrated well in 12, so they
don't matter.  The dorsal process is clearly broken off in figure 7B, making
it appear much shorter than the caudal process.  I agree figure 12 is
slightly confusing, they might have mislabeled the processes.  Then again,
you would expect the anterior process to be broader and more complex, as
suggested by their labels.  No matter which way you orient it though, it's
not T-shaped.  7B does appear sort of similar to figure 4E in Xu and Wu
(their reconstruction is horrible IMHO, looks like Varanus and doesn't match
well with the actual bones), but I doubt the illustration is very accurate.
Note it has more the quality of a rough sketch of the Eichstatt skull, with
many bones broken (qudrate, squamosal, etc.), as I suspect the quadratojugal
is.
I don't know if you'd want to fall into the trap of coding characters
present in taxa which you can imagine having "incipient" versions of it.
This is very close to coding ambiguities as which state you want or expect,
which makes your results useless.  Note that several other taxa, like some
oviraptorids and the Caudipteryx holotype also have what could be
interpreted as "incipiently T-shaped" quadratojugals, unless you want to try
to quantify the length and distinctness of the posterior process, I find it
best to only code the obviously T-shaped quadratjugals as "1".

Mickey Mortimer