RE: BEAKS, CASQUES & KINESIS

[Toby White <mwhite@houston.rr.com>]

I understand that the traditional functional explanation of the cassowary 
casque is as a "helmet" for rapid movement in forested areas.  Beyond this 
 and display, are there any other functional aspects  to the casque in 
hornbills, cassowaries, or oviraptors for that matter?

Interesting, possibly relevant sidelight.  Tinamous are weak and 
uncoordinated flyers.  If startled in a wooded area, they may take off, run 
into branches and cause serious damage.  That's one weird, but conceivable, 
function for the original development of a structure of that sort.

On Tuesday, February 29, 2000 9:50 AM, darren.naish@port.ac.uk 
[SMTP:darren.naish@port.ac.uk] wrote:
> 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.

Casuariforms are also not strictly herbivorous.

  --Toby White

Vertebrate Notes at
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