Re: Psittacosaurus Complexus

["Steve Brusatte" <dinoland@lycos.com>]

On Thu, 6 Dec 2001 11:01:21   
 Jaime A. Headden wrote:
>  Now that this specimen is in a museum, we can hope that data will be 
> published on this soon. To
>that end, I second Gunter's post in asking that discussion be kept to the bare 
>bones of the
>specimen, and not about the "feathers" or whatever they are on the specimen 
>itself.

Yes, a very good idea that all of us should follow.  Hopefully the paper will 
be published, dare I say it, relatively soon...

>  However, this doesn't address the main point. To second Pete Buchholz 
> (tetanurae@aol.com), why
>does every psittacosaurid have to be *Psittacosaurus*? There's enough 
>variation among the species
>to indicate higher taxonomic nesting of some species, but not others, and 
>similarities among only
>some that indicates nesting of a few species. 

Yes!  I remember discussing this awhile ago, with me arguing that there were 
perhaps too many Psittacosaurus species.  If I recall correctly, HP Buchholz 
argued against this point.  As he knows much more about ornithischians than I 
do, I took his arguments very seriously and examined them.  With such a 
temporal and geographic range of the eight vaild species (I think it is eight) 
there isn't a whole lot of habitat overlap, which would make this number 
viable.  

However, separating these species into two or so genera (while we are still 
using genera...:-) may be something very advantageous, or at least simpler.  

>At that point, you name new taxa to include some of
>the species. With some eight valid species or so, it is one of the most 
>_prolific_ "genera" in
>Dinosauria today. Some are more primitive (i.e., more basal) than others, 
>others quite unique. I
>would like to entertain, on Pete's behalf, a discussion of possibly splitting 
>*Psittacosaurus*
>into distinct genera. The problem is, there are not that many features that 
>can be used to
>differentiate them all, and most are based on cranial material. Also, they're 
>not theropods, so I
>don't know how well the list will take to them ;) ... sorry, couldn't resist a 
>stab at the
>theropodophiles! :)

Theropods? They're all right, but the real interesting stuff is Pennsylvanian 
tetrapods.  Anyway, I second the beginning of such a discussion.  I really 
don't  know what characters may be used to separate and diagnose different 
genera, as I don't know too much about Psittacosaurus other than what I've 
read.  However, yes, some of the more basal forms have some interesting 
characters.  Perhaps a genera consisting of some of the more primitive forms 
may work, but I don't have any idea upon which characters to base such a 
separation.  

This is something that I would like to do more research on if I get some time 
soon, but with college on the horizion that likely won't happen.  I guess I'll 
just have to make time!

Steve

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