Re: T-Tip

["Jaime A. Headden" <qilongia@yahoo.com>]

Mickey Mortimer wrote:

<I know several people (including Tom Holtz) believe
tyrannosaurs, ornithomimids and troodontids form a
monophyletic group. Try as I may, however, I just
can't find many synapomorphies to link them together.>

  Actually, recent analyses, such as those
contemporized in Padian, 1997 [Enc. of Din.] and
Padian, Hutchinson, and Holtz (1999) and the
forthcoming Holtz GAIA paper, previously presented in
the 1999 Ostrom and SVP symposia, suggest that
Arctometatarsalia is polyphyletic and of little use
phylogenetically; likewise Bullatosauria, but this
group can actually be rescued.

<Sure, an arctometatarsalian metatarsus is shared by
all three, but is absent in the Thai ornithomimid>

  The what? Pardon my stupidity, of course ... :)

<and probably Harpymimus>

  Has the dromaeosaur/coelurid/oviraptorosaur
condition of a pinched mtIII, but without contact of
II and IV; therefore, not the arctometatarsalian
condition as per Holtz (1994)

<(not to mention the Tonouchisaurus rumors). In
addition, it obviously convergently developed in
caenagnathids, mononykines and Protoavis (whatever
it/they is/are).>

  From what I've seen, *Protoavis* lacks this
condition, but this "pes" may or may not be a pes.
Mononykines are so arctomet it's not funny, and yeah,
caenagnathids have the condition, but based on being
bracketed in most phylogenies by non-arctomet taxa
(dromies, therizinos, and ovis), this is almost
certainly convergent.


=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

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