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Re: lizard & dino lips (was: hadrosaur defence)

At 06:40 PM 5/11/97 EDT, Sam j hogan wrote:
>Now, that brings up an interesting question.  Did they have lips? 
>Lizards don't  ...  Birds DON'T.  In fact all of the living reptiles
> or dino decendents don't.  So, did dinosaurs?  Did some have them
> and some not? 

Probably the last.

The presence of vascular traces on the maxilla and dentary of T. rex
strongly suggests it had lips, or perhaps even cheeks (though that is much
less likely).

On the other hand the toothless ornithomimids almost certainly were like
modern birds in possessing a beak instead of lips.

Most ornithischians have a recessed tooth row, with a vascularized bony
shelf above (maxilla) and below (dentary) them.  This is usually
interpreted (with good reason) as implying that they had cheeks.  On the
other hand the structure of the predentary and premaxilla of most
ornithischians indicates that the front part of the mouth usually had a
beak.  Thus a hadrosaur face would look rather like a horse with a beak.

May the peace of God be with you.         sarima@ix.netcom.com