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Ceolophysidae, the fossils say NO! ;)



Here goes...
Alex Downs from the Smithsonian (where he has prepared MANY of the specimans
which came out of Ghost Ranch), told me recently that there is not enough to
seperate Syntarsus from the Ghost Ranch Theropods (GRT), and that, if
Ceolophysis is not the valid genus, then Syntarsus is.
     Many people have raised the Ceolophysis-as-valid-Ghost Ranch-genus
before, and the current move to re-refer the specimens seems good.  I would
be VERY surprised if there really are more species at GR, it is, as several
posters have pointed out, far more likely that the range of GRT variance
comes extremely close to Syntarsus, and near Ceolophysis.  As GSP would then
point out "when that happens, it's a good bet your looking at a species
difference." (_Predatory Dinosaurs of the World_, GS Paul).
     To respond to Nick, as far as I know, head crests, especially amongst
ceratosaurs, where they are relatively common, are probably not sufficient to
distinguish genera.  As a sexual display device, and easily elaborated from
the lacrimal crests already present, it is likely they evolved for species
differentiation (the real distinguishing feature of Syntarsus rhodensis is
the "narial Fossa"(?), which is an opening in the skull roof bordered by the
lacrimal, the nasal, and (I believe) the prefrontal).  If Tim Rowe referred
S. kayentakae to Syntarsus, I'm sure he checked numerous derived features
before doing so (as far as I can determine, the default is to name a new
genus, and only rarely are congeneric theropod species named).  I have only
seen a passable cast of the specimen,
and I can only tell you it looks a heckuva lot like Gregory Paul's
Coelophysids.
     Therefore, we have something that looks more like Nick's Option 2:
     Coelophysis bauri
     C. longicolli (if valid, probably needs redescription?)
     C. sp (the new specimen referred to in other posts, if not C. bauri)
     Syntarsus colberti (or should this be S. bauri ?)
     S. rhodensis
     S. kayentakae

     However, the alert reader will note that I have ascribed a
characteristic to Syntarsus which is not present in the GRT specimens.  If we
consider the "narial fossa" a generic difference (although I fail to see how
it is a functional difference, it's just weird), or if we use the character
of "lacrimal extends to ventral margin of rostrum, preventing
premaxillary/jugal contact" as a generic difference, then the GRTs are a
valid taxon, and, unfortunately, are Rioarribbasaurus (this ranks up there
with Giganotosaurus as one of the *worst* names given to an extinct
creature).
     As far as I can see, the idea of reapplying Coelophysis to the GRTs is
absurd.
     >Whew< (Gulp before I write the next, unrelated posting about GRTs)
     Lot's o' good lovin'
     J.R. Wagner

---------------------------------------------------------------------------
Jonathan R. Wagner
     Graduate student sanz portfolio
     jrw6f@uva.pcmail.virginia.edu