Ceratops (was RE: Glishades ericksoni, a new hadrosauroid from Montana)

[Tim Williams <tijawi@yahoo.com>]

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 _Centrosaurus_ 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