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Nick Longrich wrote:
> [I think] Cracraft was right...when he compared the lower jaw of
> (Caenagnathus back then) to the dicynodonts. Big, anteriorly fused
> dentary beak with anteroposteriorly elongate jaw joint for a sliding
> of the jaws.
> Turns out the rest of the skull fits in pretty well with this. Many
> dicynodonts also have the extremely short skulls seen in oviraptorids,
> also if I recall have fused premaxes.
Yes, all but the earliest dicynodonts have fused premaxillae (and vomers).
Does this relate to the beak or to the development of a secondary palate?
> *downwardly vaulted palate*. As I understand things, the dicynodonts are
> believed to have a shearing motion of the jaws. So In this sheme,
> Oviraptorids could have chopped through very tough vegetation like a pair
> of those scissors you see on late-nite TV cuts through a penny.
In dicynodonts, that shearing (or grinding) occurred behind the tusks where
(as Kemp put it) an inverted knife-and-cutting board operated -- ie: a
sharp, horn-covered dentary blade was drawn back against a flat,
horn-covered upper plate. Is there anything to indicate that oviraptorids
may have also used this system?