Re: Eagle eyes

[chris brochu <cbrochu@fmnh.org>]

dbensen wrote:

> >>Palpebrals are present nearly universally among crocodilians (and have a 
> >>very broad
> distribution among crocodyliforms). <<
> Did the crocodyliforms evolve the bones independently from dinosaurs, or did 
> the
> ornithopods retain the feature while the rest of the dinosaurs lost it?

As far as I can tell, dinosaur and crocodyliform palpebrals are not homologous. 
 They
are not known from the basalmost pseudosuchians or ornithodirans - though they 
may
simply not have been preserved.




>
>
> >>No one really knows what they do, but there is a general correlation between
> palpebral size and snout shape.<<
>
> Might they have had some sort of structural function?

Yes - though I'm not a functional morphologist, so I really don't know.



chris





--
----------------------
Christopher A. Brochu
Department of Geology
Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, IL 60605

voice: 312-665-7633  (NEW)
fax: 312-665-7641 (NEW)
electronic:  cbrochu@fmppr.fmnh.org