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Re: Oviraptorosauria



>Date: Fri, 2 Apr 1999 14:31:43 -0500 (EST)
>From: "T. Mike Keesey" <tkeese1@gl.umbc.edu>
>To: dinosaur@usc.edu
>Subject: Oviraptorosauria
>Message-ID: <Pine.SGI.3.96A.990402141930.245772B-100000@umbc8.umbc.edu>
>MIME-Version: 1.0
>Content-Type: TEXT/PLAIN; charset=US-ASCII
>
>Just received a copy of Padian, Hutchinson, and Holtz's excellent new
>paper on theropod taxonomy (thanks, Patrick Norton!). I notice that, under
>their review of the usage of Oviraptorosauria, they list two definitions,
>both published in 1997:
>
>Sues: {_Oviraptor_ + _Chirostenotes_(=_Caenagnathus_)}
>Currie & Padian: {_Oviraptor_ > Aves}

Sues never explicitly defined it although his use of the term implied a
node-based definition, whereas the Encyclopedia entry (via Padian) on
Oviraptorosauria suggested a definition.  Sues read our paper and strongly
advocated a node-based definition, which by all accounts excludes
Therizinosauroidea from Oviraptorosauria (the stem would not, if Theriz. is
on that stem).  We agreed based on historical reasons (e.g. Barsbold's
original use of the name) to go against what might be construed as a clear
cut case of priority.

Besides, most folks actually publishing papers on these taxa would agree
with the node-based definition, and that's what really matters: consensus.
This is a nice example of the tug-of-war between consensus and priority; in
this case "consensus" (or what we saw as consensus, or priority of
historical usage) won hands down.

Of course, there are no clear cut rules on this.  Yet.

>They opt for Sues' definition, but on my site I'd like to use the one that
>was published first -- does anyone know which one came out first in 1997?

Sues by a hair?  But not defined, just used.  See also Barsbold 1976, 1983,
etc.

>Also, and I guess Tom can answer this better than anyone else on the list,
>why do they advocate anchoring clades with eponymous genera, then define
>Abelisauroidea as {_Carnotaurus_ > _Ceratosaurus_}? (Not that it probably
>matters much, but ...)

You're right that it doesn't matter much; _Abelisaurus_ and _Carnotaurus_
are clearly close relatives.  In this case we made an exception and used
the better known specimen (_Carnotaurus_ has a good skeleton; _Abelisaurus_
is much more fragmentary).  Just like it's a bit safer and more operational
to define archosauromorph subclades by reference to living/well known
archosauromorphs rather than to _Archosaurus_.  Again, no rules yet.

>Hmm... looks like Abelisauroidea includes Abelisauria (=={Abelisauridae +
>_Noasaurus_} Novas, 1991) ...

Yeah, as we intimate in the paper, (neo)ceratosaur taxomomy was a real pain
to deal with.  We stuck with how Novas has it, because he's working on
these taxa (and read a draft of the paper).  It is odd, and maybe it will
change later.  Doesn't bug me either way.   :)

Excellent, perceptive comments and questions.  Thanks, Mike!

                        John R. Hutchinson
                 Department of Integrative Biology
                  3060 Valley Life Sciences Bldg.
                University of California - Berkeley
                     Berkeley, CA 94720 - 3140
                      Phone:  (510) 643-2109
                      Fax:    (510) 642-1822
         http://ucmp1.berkeley.edu/people/jrh/homepage.html