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Re: Ceratops (was RE: Glishades ericksoni, ...)

> _Ceratops_ is actually excluded from 
> all proposed definitions of Ceratopsidae

? If so, that's only because it's a nomen dubium. 

Btw, "Ceratopsinae" is not used by ceratopsian experts. They 
already and always have used Chasmosaurinae. See Dinosauria, 
Dinosaur Systematics, etc. 

As for Ceratops, it may indeed be Avaceratops (or vice versa, 
actually), but that's impossible to demonstrate because 
Ceratops only includes two horncores and an OC, and as 
Tom pointed out, there are other taxa with similar PO 
horn morphology (though only one or two). 

--- On Wed, 5/12/10, Tim Williams <tijawi@yahoo.com> wrote:

> From: Tim Williams <tijawi@yahoo.com>
> Subject: Ceratops (was RE: Glishades ericksoni, a new hadrosauroid from 
> Montana)
> To: dinosaur@usc.edu
> Cc: tijawi@yahoo.com
> Date: Wednesday, May 12, 2010, 7:32 PM
> Tom Holtz <tholtz@umd.edu.
> wrote:
> > I do support the use of Saurolophinae for "the clade
> > formerly known as
> > Hadrosaurinae", and by similar token would go back to the
> > main herd in the
> > use of Chasmosaurinae for the Chasmosaurus-Triceratops side
> > of Ceratopsidae.
> > (Ceratops itself may well fall outside Chasmosaurus +
> > Centrosaurus, now that
> > we know the brow horn morphology it possesses is shared by
> > basal
> > Centrosaurinae, most Chasmosaurinae, and near outgroups to
> > Ceratopsidae.)
> To complicate things even further, it has been suggested
> that _Ceratops_ may be the same as _Avaceratops_ (i.e., that
> the type of _Avaceratops_ is a young _Ceratops_). 
> _Avaceratops_ has been considered a centrosaurine (e.g.,
> Ryan [2007], in the description of _Albertaceratops_). 
> Considering the unstable position of _Ceratops_
> (chasmosaurine, centrosaurine, or outside both), it's a poor
> choice as an eponym.  Therefore, it's probably best to
> abandon Ceratopsinae - and perhaps abandon the name
> Ceratopsidae too.  _Ceratops_ is actually excluded from
> all proposed definitions of Ceratopsidae, a clade which is
> anchored in _Triceratops_ and _C
s_ or
> _Pachyrhinosaurus_.  As Tom says, _Ceratops_ may fall
> outside of the _Chasmosaurus_ + _Centrosaurus_ clade. 
> In this case, Ceratopsidae would not include _Ceratops_
> itself.
> Cheers
> Tim