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Definitions of Ornithomimosauria
>Since I diagnose the clade Ornithomimosauria in the _Pelecanimimus_ paper,
>and there is anode in the cladogram with this name, I think
>Ornithomimosauria has been cladistically defined. That is, _Pelecanimimus_
>and all taxa sharing a more recent ancestor with _Pelecanimimus_ than with
>_Troodon_ (at least until my future work on the phylogeny of
>Ornithomimosauria will be finished).
I would STRONGLY urge you to use _Ornithomimus_ rather than _Pelecanimimus_,
so that (by definition) Ornithomimosauria will always include
_Ornithomimus_. (Gauthier's 1986 definition of "Ornithosuchia" did not use
_Ornithosuchus_, so that now _Ornithosuchus_ is not an ornithosuchian... :-( )
I would agree that the two definitions would describe the same clade, given
what we know. If, however, it turns out that (strange as it might seem)
_Pelecanimimus_ might have a more recent common ancestor with _Troodon_ than
with _Ornithomimus_, we would be stuck with _Ornithomimus_ outside of
Ornithomimosauria. I don't expect anyone will find this particular
three-taxon statement, but I'd like the phylogenetic taxonomic definitions
to be as "bomb-proof" (to use a computer programmer's term) as possible.
Thomas R. Holtz, Jr.
Vertebrate Paleontologist Webpage: http://www.geol.umd.edu
Dept. of Geology Email:firstname.lastname@example.org
University of Maryland Phone:301-405-4084
College Park, MD 20742 Fax: 301-314-9661
"There are some who call me... Tim."
-- Tim the Enchanter, "Monty Python and the Holy Grail"
---------- subtitle --[Monty Python ik den Holy Grailen]
"Tim?!? They called me TIM?!?!"
-- Tom the Paleontologist, on seeing "The Ultimate Guide to T. rex" :-)