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Re: Rigid dinosaurs

On Thu, Feb 23, 2006 at 09:46:56AM -0700, Jerry D. Harris scripsit:
> >Well, what else _is_ there?  I don't see how a ligament embedded in
> >the cervical soft tissue can be a sexually selected (which is of
> >course the usual get-out clause for Inexplicable Mystery Morphology).
> Me neither!  I just meant I haven't yet come up with a good hypothesis
> about what kinds of non-sexual selective pressures guided the
> evolution of _Rhea_ toward having a nuchal-ligament-like elastic
> ligament system.

Why can't it be sexual selection?  Ostrich courtship dances involve lots
of twisty neck movements; there doesn't seem to be any obvious reason
why rhea courtship dances couldn't. 

If they do, there's an opportunity for sexual selection of a neck
ligament there.