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RE: Ceratopsine phylogeny questions

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of Michael Erickson
> Tim Williams wrote:
> > So "genera" such as _Brachyceratops_ and _Monoclonius_ are 
> regarded as 
> > nomina dubia
> Hate to be a party crasher here, but Dodson (1992) showed 
> that _Monoclonius_ was a vlid genus. _Brachyceratops_, 
> however, is indeed a jeuvenile of some other centrosaurine, 
> probably _Styracosaurus_.
> Ref.
> Dodson, Peter (1992). On the status of the ceratopsids 
> _Monoclonius_ and _Centrosaurus_. In: Dinosaur systematics: 
> Approaches and Perspectives. Cambridge University Press. pp. 
> 231 - 245. ISBN 0521438100.

Not universally accepted by any means, in light of more recent discoveries
of centrosaurine populations.

> > On that basis, _A. ajax_ would be regarded as a nomen dubium. This 
> > would render>_Brontosaurus_ a valid genus,

But Iff that basis (that juveniles weren't acceptable as types, which they
currently are) were accepted. Sad to say, the case for _Brontosaurus_ is not
particularly good...

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
Faculty Director, Science & Global Change Program, College Park Scholars
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA