In a recent correspondence (20 April 2000, Re: Jurassic Marginocephalians) you wrote-
"I've also heard doubts regarding the identity of Yaverlandia. Such as it might represent the skull fragment of an ankylosaur, and not a pachycephalosaur".
Have you got any further information regarding the identity of Yaverlandia bitholus?
Maryañska (1990) stated that "Hopson (1979) doubted the relationship of Y. bitholus with other pachycephalosaurs because of the structure of its fragmentary endocranial activity. Although these differences in the endocranial cast are significant, it is also true that Y. bitholus shares with other pachycephalosauridae two characters not found in any other ornithischians: the thickening and doming of the skull roof and the textured nature of its dorsal surface" (pp.574-575).
Are there any ankylosaurians with skull roof thickening and texturing?
Maryañska, T. 1990 Pachycephalosauria, in Weishampel, D. B., Dodson, P. & Osmólska, H. 1990 (eds.) The Dinosauria, University of California Press, pp.564-577.