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



Thomas R. Holtz, Jr. <tholtz@umd.edu> wrote:


> It depends on what the agreed upon definition of Ceratopsidae is
> to be. If it is (for example) Centrosaurus + Chasmosaurus, than
> Ceratops might well be a non-ceratopsid. If instead Ceratopsidae is
> defined as Ceratops + Centrosaurus + Chasmosaurus, than it would be
> included by definition, but might be outside Chasmosaurus > 
> Centrosaurus and Centrosaurus > Chasmosaurus.


But... we'll never know where _Ceratops_ sits in ceratopsian phylogeny.  
_Ceratops_ is *never* included in a phylogenetic analysis, because it is a 
nomen dubium.  

I'm not saying _Ceratops_ *should* be included in a phylogenetic analysis; I'm 
only saying it *can't* be.  This simple fact makes it impossible to determine 
the content of Ceratopsidae if _Ceratops_ is a specifier.  For example, what if 
_Avaceratops_ comes out as a sister taxon to the Chasmosaurinae+Centrosaurinae 
clade.  Is _Avaceratops_ a ceratopsid?  We could only know this if _Ceratops_ 
is also included the analysis.  But it isn't...


T. Michael Keesey <keesey@gmail.com> wrote:

> Probably the best solution, since both relevant
> nomenclatural codes (ICZN and the draft PhyloCode) require Ceratops 
> montanus to be within Ceratopsidae by definition.


IMHO, the best solution is to abandon Ceratopsidae altogether. We've abandoned 
other family-level names that have been deemed to be based on dubious genera 
(Deinodontidae, Trachodontidae, Titanosauridae, etc), so why not abandon 
Ceratopsidae too?  Having a definition of Ceratopsidae that includes 
_Ceratops_, for the sole purpose of maintaining the name Ceratopsidae, strikes 
me as special pleading. 


Cheers

Tim