Re: Avaceratops

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

>In a recent posting by Jeffery Martz he listed Judith River ceratopians,
>including Avaceratops lammersi. According to recent references I have seen,
>a) the species name is now lammersorum, and 
>b) the whole thing is now included with Monoclonius.
>Am I correct?
>
If some paleontologists are correct, 'Avaceratops' and 'Monoclonius' are not
taxa: they are growth stages in the life cycle of centrosaurines before they
reach maturity (juvenile and subadult, respectively).  This will be
discussed in a forthcoming article by Sampson, Ryan, and Tanke in the
Zoological Journal of the Linnean Society.  The article title, by the way,
is "Craniofacial ontogeny in centrosaurine dinosaurs (Ornithischia:
Ceratopsidae): taxonomic and behavioural implications".

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