Re: Avaceratops and Ceratops (was RE: First International Phylogenetic Nom...)

[Paul Penkalski <turtlecroc@yahoo.com>]

Here's my 2 cents on this. In our 1999 paper, Dodson
and i 
concluded that _Ceratops_ is a nomen dubium because
the 
material - essentially just two horncores - is
insufficient for 
diagnosis. So even if Avaceratops were really
Ceratops, it is 
doubtful one would ever be able to demonstrate it. (at
least 
not in this lifetime). Still, it's a fun puzzle to
play with. 

Cheers,
Paul

--- Tim Williams <twilliams_alpha@hotmail.com> wrote:
> Jaime A. Headden wrote:
> 
> >   To use *Triceratops,* the next oldest available
> taxon that is considered
> >valud, one could just name a new clade
> Triceratopsia, or define the clade
> >as an apomorphy-based taxon,
> 
> Why would we need to go to all this trouble? 
> Ceratopsia can be a valid 
> name, irrespective of whether or not _Ceratops_ is a
> valid genus.  
> Ceratopsidae (+Ceratopidae), on the other hand... 
> (To cite an analogous 
> example: Titanosauria, but not Titanosauridae, can
> be valid names if 
> _Titanosaurus_ is a nomen dubium.  Ditto for
> Hadrosauria/Hadrosauridae.)
> 
> >On the other hand, some
> >HAVE suggested *Ceratops* may be valid ... I think
> Dodson suggested
> >*Avaceratops* and *Ceratops* may be synonyms or
> sister-taxa. I forget.
> 
> Here's what I wrote over 4 years ago 
>
(http://www.cmnh.org/dinoarch/2000Jan/msg00354.html),
> regarding 
> _Avaceratops_, based on new cranial material:
> 
> Penkalski and Dodson's paper contains a few
> interesting tidbits.
> (1) The orbital horns of this new skull show a
> striking resemblence to the
> horn cores of the type of _Ceratops montanus_, in
> their shape and
> orientation (directed outwards at quite a large
> angle).  Could _Avaceratops_
> be a juvenile _Ceratops_?  (For those who believe
> that _Ceratops_ is a
> defunct genus, read on...)
> 
> (2) Even if this new skull does not belong to
> _Avaceratops_ it belongs to a
> closely related genus, probably a basal ceratopsid
> like _Avaceratops_.
> Maybe _Ceratops_?  (_Ceratops_ is considered a nomen
> dubium by Penkalski and
> Dodson, but I've heard of good material from the
> "Milk River" site that may
> pertain to this genus.  Anybody know about this?)
> 
> (3) In another paper in the same issue of JVP,
> Sereno calls the sister-group
> to the Centrosaurinae Ceratopsinae rather than
> Chasmosaurinae.  [snip]  At 
> any rate,
> there's no good evidence that _Ceratops_ is a
> chasmosaurine (see (1) and 
> (2)).
> 
> 
> 
> Tim
> 
>
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