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Re: ORNITHISCHIANS :-)
George Olshevsky (Dinogeorge@aol.com) wrote:
<So it's pretty much a marginocephalian apomorphy, yes? Or are
you saying this is an ornithischian plesiomorphy?>
It is my understanding from having poured over the literature
that while a cingulum is present in both ankylosaurs, and
stegosaurs, a cingulum only occasionally pops up in traditional
hypsilophodont groups, it is lacking in *Lesothosaurus* and
*Pisanosaurus*, the latter which also lacks disinct
transformation of a phyllodont tooth (there is no primary ridge,
no denticulation ridges on the surface of the tooth, no packing
or medial orientation of the mesial edges of the crowns --
making it the most plesiomorphic of all ornithischian jaws).
Jaime A. Headden
Where the Wind Comes Sweeping Down the Pampas!!!!
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