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RE: Stenopelix valdensis

Michael Lange wrote-

I heard that Sullivan has recently made Stenopelix an Ornithischia indet. I've seen the specimen >myself some years ago on display at the small Geological Museum in Goettingen. The skull is not >present, but should have been preserved when the quarry workers found the skeleton (when I >recall correctly). Still, its a nice and interesting specimen. What are the reasons why Sullivan says >its no Marginocephalian anymore.

Because few pachycephalosaurs preserve good postcrania, so he's far too cautious about referring postcrania to the clade (if he can't prove that most pachycephalosaurs had a trait, he considers the trait 'weak').
Also he questioned the absence of pachycephalosaur postcranial synapomorphies in outgroups, with no examples to show why he questions it.
Finally, he likes Coombs (1979) outdated idea of pachycephalosaurs being an ankylosaur sister group better, and Stenopelix lacks a pelvic character those two clades share. Needless to say, Yinlong nicely blows that proposed relationship out of the water.
So basically Sullivan's reasons are worthless and should not be given any weight.

Mickey Mortimer