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Re: Sereno's work & public appeal



Incidentally, his chapter in the Ostrom Symposium volume on alvarezsaurids
is excellent.  He shows that most of the analyses finding them as
maniraptorans are "Sereno-esque" too, leaving out all of his alvarezsaurid +
ornithomimosaur synapomorphies.  Of course, he left out nearly all of the
alvarezsaurid + maniraptoran synapomorphies in his analysis, so no one's
being objective. :-)  Except later analyses like Holtz (2000/2001), mine and
Norell et al. (2001), of course.  He includes some wonderful illustrations
of Shuvuuia's skull (which Chiappe et al. 1998 should have really considered
doing).  However, his rebuttals of the avian characters present is less than
convincing.
1. Ectethmoids, not enlarged prefrontals.  While I agree they are
prefrontals, he merely shows they are paired, but Chiappe et al. said they
were paired originally, they just note that no other prefrontals are known
to contact ventral to the nasals/frontals.  Sereno does not refute this.
2. Triangular palatine.  Sereno notes the palatine is not "short and
triangular", as he says Chiappe et al. described it, but rather is elongate
and "extends between the antorbital fenestrae as a broad anterodorsal ramus
towards the vomera".  Actually, Chiappe et al. said it was "long and
slender, lacking the jugal process and tetraradiate aspect...".  The
triradiate feature is what's important, and Sereno does not actively refute
this.
3. Large foramen magnum.  Sereno notes that though a juvenile Shuvuuia has a
foramen magnum 180% wider than the occipital condyle, an adult has a 150%
ratio.  However, this is still larger than all non-ornithothoracine
theropods, ornithomimids having a ratio of 82-86% for example.
4. Low number of caudal vertebrae (<26).  Correctly predicts Shuvuuia has a
larger caudal count.
5. Laterally compressed pubic shaft.  Notes Patagonykus has the character,
but Shuvvuia, the Hell Creek mononykine and Confuciusornis don't.
Interesting.
6. Ischial symphysis absent.  Supposedly present in Shuvuuia, Archaeopteryx,
Confuciusornis and enantiornithines.  He doesn't refute it's absence in
Parvicursor though.  And I have a hard time picturing Confuciusornis with
one, given both the statements to the contrary and photos in Chiappe et al.
(1999).  Confusing....

Mickey Mortimer