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RE: dinosaur beaks and ora speeds
Thomas R. Holtz, Jr. wrote:
Well, I would add that in living beaked reptiles (turtles, birds), as well
as extinct forms generally accepted as beaked (ornithomimosaurs, for
instance) there is a relatively sharp edge between the lateral and ventral
surfaces of the maxillae. In contrast, in _Alioramus_ and _Carch._ there
is a curved surface grading the lateral into the ventral surface.
If I understand you correctly, in ornithomimosaurs the cornified
rhamphotheca provides the cutting edge to the upper (and lower) jaw, as in
the beaks of turtles and birds. IMHO, _Alioramus_, _Carcharodontosaurus_,
_Majungatholus_ and other non-maniraptorans, by contrast, were not "beaked",
but nevertheless had a cornified zone expressed on the dorsal rostrum
(perhaps continuous with any pre- or postorbital ornamentation). Thus, in
these forms this sheath was not trophic in function, but decorative or
(?)thermoregulatory and did not extend to the oral cavity.
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