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The position of Troodonts




Jaime,
I was just rereading your post of May 14th (below), where you say that Troodontidae perhaps preserved the last vestiges of the leg and braincase that were lost in dromaeosaurs, therizinosaurs, oviraptors, and avians. That's a very interesting observation.
I am curious what vestiges of the leg and braincase might be of particular phylogenetic significance for how troodonts may be related to various "maniraptoran" groups. Any possibility that Troodontidae paraphyletically gave rise independently to two or more clades of maniraptorans? Or is it more likely Troodontidae is holophyletic, but just rather conservative and relatively slow evolving compared to other maniraptorans?
------- Ken
*******************************************************
From: "Jaime A. Headden" <qilongia@yahoo.com>
Reply-To: qilongia@yahoo.com
To: dinosaur@usc.edu
CC: david.marjanovic@gmx.at
Subject: Re: The position of tyrannosaurs (was Re: Armour Symposium Recollections)
Date: Mon, 14 May 2001 21:22:57 -0700 (PDT)

  Arctometatarsalia {Ornithomimus <- Neornithes} is still
plausible, and does not require tyrannosaurs in its content,
though this is what Holtz suggested in 1994 and 1995 (in
Sereno's 1999 phylogeny, alvarezsaurs as ornithomimosaur
relatives would be members of Arctometatarsalia (a stem) which
would contain Ornithomimoidea (a node)); data seems to point to
the synapomorphies being tyrannoraptoran {Tyrannosaurus +
Neornithes} in nature that were reversed in maniraptorans,
perhaps with Troodontidae having preserved the last vestiges of
the leg and braincase that were lost in the dromaeosaur,
oviraptorosaur, therizinosaur, and avian lineages.

Maniraptoriformes == {Ornithomimus + Neornithes}.

=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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