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RE: Maniraptoriformes

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Ken Kinman
>      Getting late and probably should be resting my brain instead
> of pushing
> it, but have one more question for today.
>      Is Coelurosauria considered to be a more stable and less
> controversial
> taxon than Maniraptoriformes (which may or may not include
> tyrannosauroids).

As father of the Maniraptoriformes, and long-time pal of Coelurosauria, I
think I can help answer this...

Well, first: define what you mean by "stability".  Is it stability of
membership, stability of diagnosis, or stability of definition?

Working backwards: stability of definition is equally strong for both.  They
have clear, and mutually exclusive, definitions: Maniraptoriformes = all
descendants of the most recent common ancestor of _Ornithomimus_ and modern
birds, and Coelurosauria = birds and all taxa closer to birds than to

In terms of stability of diagnosis, they are comparably strong (or weak), in
that there remain a suite of primitive taxa which may or may not belong to
that clade: depending on the inclusion or exclusion of these taxa, the
diagnosis of that clade changes. (1).  Said taxa include Compsognathidae,
_Coelurus_, _Deltadromeus_, _Ornitholestes_, _Proceratosaurus_, and
_Scipionyx_ (and Tyrannosauridae) for Maniraptoriformes (i.e., each and
every one of these may or may not be a maniraptoriform), and _Gasosaurus_,
_Monolophosaurus_, _Marshosaurus_, and a few others which may or may not be
basal coelurosaurs (or basal carnosaurs, or just outside Avetheropoda).

Ditto stability of membership, for the reasons noted above.

Neither of these clades are regarded as particularly contraversial, any more
so than Neornithischia/Cerapoda or Marginocephalia.

Hope this helps.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-314-7843