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

[David Marjanovic <david.marjanovic@gmx.at>]

>  Of course there's nothing stopping someone from including _Ceratops
>  montanus_ in a phylogenetic analysis.  But this is not the same as
>  saying that there is a *good* reason for including _Ceratops
>  montanus_ in a phylogenetic analysis.
>
>  Your suggestion is just special pleading.  _Ceratops_ is the
>  name-bearing genus for the Ceratopsidae, and therefore you are
>  pretending it's a useful OTU for a phylogenetic analysis.  But it
>  isn't.  The type material of _Ceratops montanus_ could belong to any
>  number of derived, brow-horned ceratopsians - including (as noted by
>  Ryan, 2007) _Albertaceratops_.  In fact, decent cranial material that
>  was thought by Trexler and Sweeney (1995) to belong to _Ceratops
>  montanus_ was later assigned to _Albertaceratops_.
>
>  Including a deliberately phoney OTU like _Ceratops_ in a phylogenetic
>  analysis alongside valid OTUs (like _Albertaceratops_) defeats the
>  entire purpose of a phylogenetic analysis, which is to establish
>  relationships among taxa.

It's indeed a bad idea to include OTUs that are possibly paraphyletic 
with respect to other OTUs in the same data matrix.

Of course there's an easy way to get around this: make a specimen-level 
analysis, and put *Ceratops* in.