Re: Monoclonius

[Thomas_R_HOLTZ@umail.umd.edu (th81)]

>I've become rather confused about the status of Monoclonius. It doesn't seem
>so long ago that some authors were trying their hardest to put Avaceratops,
>Brachyceratops etc into Monoclonius, but recent postings to this list
>suggest strongly that Monoclonius species are likely to be juveniles of

Not juveniles, but subadults.

>other ceratopian species. So, just what is the current position? If
>Monoclonius is juvenile of other unknown species, is Monoclonius retained as
>a genus until the "unknowns" are identified; does it become a nomen dubium,
>or what? And why the change? Is it due to new material, or re-investigation
>of old stuff (after all, Monoclonius material has been around for a long
time)?

I would strongly suggest that you get a hold of the proofs of Sampson et
al.s forthcoming paper, previously cited.  I know that one of the authors,
Darren Tanke, reads the list.  If the paper is similar to the various talks
given by the authors for the past few years, it should be a treat!

(Incidentally, from what I recall, the evidence is found in the fairly
common centrosaurine monospecific/paucispecific bonebeds.  The fossils show
an ontogenetic series of forms through the "Brachyceratops", "Monoclonius",
etc. morphs, up to the distinctive adult forms (Centrosaurus, Einiosaurus,
Pachyrhinosaurus, etc.).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Dept. of Geology
University of Maryland
College Park, MD  20742
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)
Fax: 301-314-9661
Phone:301-405-4084