Re: Eagle eyes

[chris brochu <cbrochu@fmnh.org>]

Palpebrals are present nearly universally among crocodylians (and have a very 
broad
distribution among crocodyliforms).  In general, the more robust the snout, the
larger the palpebral - and in very blunt-snouted forms (Paleosuchus, 
Osteolaemus, a
few fossils), the palpebral forms from multiple ossifications.

No one really knows what they do, but there is a general correlation between
palpebral size and snout shape.




chris


dbensen wrote:

> I was studying some skeletal reconstructions of ornithopods today and I 
> noticed
> something that I had never thought much of before.  Many (I won't say all, for
> there may be exceptions) ornithopods have a nob of bone extending over their
> eyes.  This palpebral bone, as it is called, would give  them a fobidding 
> "eagal
> eye" (that forbidding glare common to raptors) in life (I remember reading
> something to the effect in a Gregory Paul essay).  My question is this: "Why 
> would
> you evolve a palpebral bone?"  Obviously, it is something good, for both 
> raptors
> and ornithopods had them, and since predatory dinosaurs didn't have them, must
> have evolved the structure independantly (right?)
>
> So, what is their function?
>
> Thanks
> Dan

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

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