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Re: Ornithomimid beaks



> If the theory of theropod beak formation that has the horn butting pads,
> lacrimal horns, and so on extending down the snout until close enough to
> the mouth to be exapted as a cutting surface is correct, you'd expect
> beaks to be initially right at the tip of the mouth.  (Although I am not
> at all sure how that theory handles *lower* beaks.)

Don't know that one, but the hypothesis that links beaks and egg teeth
(which explains why therians never evolve beaks) predicts the same. But I'd
expect teeth behind, not simply nothing, which the paper implies.

> [...] as soon as there *was* a beak
> there, there was strong selection pressure against teeth.  The sharp jaw
> margins may just be side effects of tooth loss.

Sure, but what covered the jaw margins, if not a beak?
*Pelicanimimus* which has such sharp margins on the caudal parts of the
maxillae looks even stranger now...