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BEAKS, CASQUES & KINESIS
A few comments on Nick's recent post. Nick wrote...
> In some [birds], e.g. hornbills, bony contribution to a horn structure
> (the casque) may be fairly minimal.
I have seen sectioned hornbill skulls and recall that, in those with
a casque, a hollow bony crest does take up much of the casque's
internal volume. I also have photos of rhino hornbill (_Buceros
rhinoceros_) skulls: in the skull, the crest is pretty much the same
shape as is the casque in the live bird. I suppose this may not the
case for all species though. Cassowaries certainly have casques where
the bony core is small compared to the whole structure: in the two
larger species the casque itself may be three or four times taller
than the bony crest. The bony crest is also very fragile, in contrast
to its horny sheath.
Nick also drew attention to possible analogy between dicynodonts and
oviraptorosaurs. WRT this, I think it's interesting that Sues and
Reisz (1998) suggested that some dicynodonts could have been
omnivores or carnivores: that they are beaked and relatively
graviportal does not prove that they were herbivores.
Incidentally, for those of you at the Oviraptorosaur Synapomorphy
Mini-Symposium in Denver last year (Adams Mark Hotel), I have learnt
that the David Smith who wrote the oviraptorosaur jaw motion paper IS
the same David Smith who has recently been publishing on
the systematics of _Allosaurus_ (J. Kirkland, pers. comm. 2000).
> (I recall one of the black hills guys arguing at
> Dinofest that even Rex has pretty decent kinesis in a lot of
In her work on finite element analysis and stress distribution in
theropod skulls, Emily Rayfield has proposed that _Tyrannosaurus rex_
had kinetic zones at the postorbital-jugal suture and elsewhere
(data presented at Progressive Palaeontology 1999, Bristol Univ.).
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