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Re: Oviraptorosauria (and Abelisauroidea)

On Sun, 4 Apr 1999, John R. Hutchinson wrote:

> >From: "T. Mike Keesey" <tkeese1@gl.umbc.edu>
> >
> >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.

Okay. I kind of liked the other scheme better (with Oviraptoroidea as the
node group), but, since my site isn't about my personal opinions, but
about what's correct and what's used, I'll switch back.
> >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).

But if

A) They are *clearly* close relatives, where's the danger in using
_Abelisaurus_ as the anchor?

B) There is any doubt due to _Abelisaurus_' fragmentary nature,
wouldn't it be safer to anchor with _Abelisaurus_ anyway?

Just being picky. I think the "Ornithosuchia mistake" should be avoided.

> 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.

I didn't even know there *was* an _Archosaurus_... named before
Archosauria? (Certainly wouldn't want to anchor Dinosauria with
> Excellent, perceptive comments and questions.  Thanks, Mike!

Thank YOU. I may not know much about anatomy, paleoecology, paleogeology,
etc., but I do know taxonomy!

--T. Mike Keesey                                    <tkeese1@gl.umbc.edu>
WORLDS                                  <http://www.gl.umbc.edu/~tkeese1>
THE DINOSAURICON                               <http://dinosaur.umbc.edu>