Re: Ceratops analyzed in the Sampson et al. (2010) matrix

[Tim Williams <tijawi@yahoo.com>]

Michael Mortimer <mickey_mortimer111@msn.com> wrote:


> With all of this discussion of Ceratops lately, isn't it
> about time someone do some science to solve the question of
> what it is?  [snip]
> Note it also has a unique combination of characters, so it
> not a nomen dubium.  It differs least from Utahceratops
> (except for the long brow horns) and Anchiceratops and
> Arrhinoceratops (except for the straight, not recurved, brow
> horns).


This is great stuff, Mickey.  However (yes, there's always a however), to play 
Devil's Advocate....


(1) This same analysis also found _Triceratops_ to be distinct from 
_Torosaurus_ (and _Nedoceratops_).  I don't need to elaborate on this one.  ;-)


(2) What happens if you include the holotype for _Eoceratops canadensis_ in the 
analysis?  (This is NMC 1254, which includes a partial skull, and is apparently 
a juvenile)?  The relatively long brow-horns are considered to be a sign of the 
specimen's immaturity.  Does _Eoceratops_ pop up in the tree as a separate 
taxon?


The point I'm making is that because brow-horn characters (shape, length, 
orientation) are prone to ontogenetic variation, a unique combination of 
brow-horn characters might not be a sufficient diagnosis to validate 
_Ceratops_.  Just saying....




Cheers

Tim