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Compsognathus, carnosaurs, and torvosaurids



Well, a lot of this has already been summed up over the weekend, but some
updates/corrections:

In my Gaia paper compsognathids do fall out as basal maniraptorans; in a
modified version of the same matrix in the forthcoming Ostrom symposium
volume, they fall out equally parsimoniously as basal arctometatarsalians or
basal maniraptorans; in the SVP 2K matrix, they fall out again as basal
coelurosaurs (indeed, one of the basalmost clades, with forms such as
_Ornitholestes_ and _Coelurus_ further up the tree).

As for Carnosauria: there has been one (and only one) taxon which has been
in every single incarnation of Carnosauria, namely _Allosaurus_.  Hence my
proposal of its use as the anchor taxon for Carnosauria.

Torvosauridae is defined phylogenetically by Sereno (1998) as all
spinosauroids closer to _Torvosaurus_ than to _Spinosaurus_.  I'm not a big
fan of this kind of formulation (i.e., inclusion of the larger taxon
"spinosauroid" within the definition),  and if you reformulate this
definition to read "all taxa closer to _Torvosaurus_ than to _Spinosaurus_"
than in some phylogenies (my GAIA tree, for example) hummingbirds and
oviraptorosaurs and lots of other critters wind up being torvosaurids.
Megalosauridae and Megalosauroidea have not at present been phylogenetically
defined in the formal literature.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796