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RE: I'm back...
> From: firstname.lastname@example.org [mailto:email@example.com]On Behalf Of
> David Marjanovic
> > > - Is it possible that I have found, in the famous illustrations, a
> > > synapomorphy for Arctometatarsalia: a rugose crest in the
> midline on the
> > > nasals? Do troodontids have such a thing (ornithomimo- and
> > do, dromaeosaurs don't, neither do oviraptorosaurs primitively)?
> > [...] Regarding troodontids, both Byronosaurus and
> > Saurornithoides mongoliensis appear to have smooth nasals.
> While that of
> > Saurornithoides junior looks textured in my bad photocopy, it's
> not rugose
> > in the way tyrannosaurids' are as far as I can tell.
> I see. So unless it comes out as an arctometatarsalian synapomorphy,
> reversed in troodontids, in a parsimony analysis, I apparently
> can't use it.
A) That assumes that troodontids are arctometatarsalians, a position no one
I know of currently holds.
B) What do you mean "apparently can't use it"? Observations are
observations; we don't play the old game (which, sadly, was the operational
paradigm of too many traditional taxonomists, and not a few cladists) of
"counting the hits and ignoring the misses". If you see a shared feature
with a non-global (for the level you are examining) distribution, it is fair
game as a potential synapomorphy, and should a priori be treated as such.
Thomas R. Holtz, Jr.
Department of Geology Director, Earth, Life & Time Program
University of Maryland College Park Scholars
College Park, MD 20742
Phone: 301-405-4084 Email: firstname.lastname@example.org
Fax (Geol): 301-314-9661 Fax (CPS-ELT): 301-405-0796