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Re: ORNITHISCHIANS :-)



George Olshevsky wrote-

> This is not a character I would use. The acetabulum is partly closed in
all
> stegosaurs by an acetabular pocket off the pubis--an enlargement of the
pubic
> peduncle--which is a good stegosaur apomorphy (literally all known stegos
> have it). There is nothing like this in any ornithopod, or in any other
> ornithischians for that matter.

Interestingly, ceratopsids have independently evolved this character (Sereno
and Dong, 1992).

> Stegosaurs represent a distinct branch of Ornithischia that may or may not
> have anything to do with the ankylosaurs. They differ from ankylosaurs in
> practically all aspects of their skeletal anatomy, so if they do share a
few
> minor similarities these may or may not be meaningful.

This statement doesn't make sense.  It doesn't matter how different taxa
are, just what derived characters they share (no matter how minor).

Mickey Mortimer