Re: Distributions of morphological characters and more

[Jordan Mallon <jordan.mallon@gmail.com>]

On 8/17/05, David Marjanovic <david.marjanovic@gmx.at> wrote:
> ----- Original Message -----
> From: "Nick Gardner" <nick.gardner@gmail.com>
> Sent: Wednesday, August 17, 2005 4:19 PM
> 
> > Has anyone else noticed there is a tendency in many cladistic analyses      
> >   > >(especially ornithischians) to focus on cranial characters, while 
> > paying little (if  > >any) attention to those of the postcrania?
> 
> Yes. I've also noticed that the chapters on Ankylosauria, Pachycephalosauria 
> >and Ceratopsia in both editions of The Dinosauria almost completely ignore 
> the >postcrania.

More than anything, it probably has to do with being told for decades
and decades that the postcranium of many ornithischians (e.g.
ceratopsians, hadrosaurs, etc.) is so conservative across family-level
clades that it is of little use taxonomic use.  So,
beautifully-preserved and complete postcrania are ignored on that
assumption.  Here at the CMN we have some of the most complete
ceratopsid skeletons in the world, but they've been totally ignored
for 80-90 years because they aren't "useful" or "valuable."  But
that's slowly starting to change.  For example, Rob Holmes and Michael
Ryan are in the midst of describing the skeleton of the type of
Styracosaurus albertensis, and I've just begun to describe the
postcranium of Anchiceratops.  There's similar work being done on
hadrosaurids, too (e.g. Robin Cuthbertson's work on
Brachylophosaurus).

> > Is this an artifact of limited material or research
> > being done, or does it truly represent a lack of characters from the
> > postcrania? I'm inclined to believe the former.

Definitely the former.  Lack of material and lack of interest, in many
cases (everyone's doing theropods!).
 
-- 
Jordan Mallon

BScH, Carleton University
Vertebrate Palaeontology & Palaeoecology

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