Re: Ornithomimid beaks

["Mickey Mortimer" <Mickey_Mortimer11@msn.com>]

T. Mike Keesey wrote-

> I said WITHIN those clades, not for the whole clade. And _Sinornis_ other
> basal pygostylians did have beaks. _Protarchaeopteryx_'s skull isn't even
> known, is it? (And it isn't a pygostylian, if you meant to imply that.)
> _Archaeopteryx_ isn't supposed to have had a beak, AFAIAA, but I said
> *within* _Aves_, not *in all* _Aves_.

Although the skull of Sinornis is very poorly preserved, those of the
related Cathayornis and Largirostrornis do not differ much in tooth
morphology or distribution compared to Archaeopteryx.  Why would basal
pygostylians have beaks?
Protarchaeopteryx's skull is known, just very fragmented and poorly
described.  There were four large premaxillary teeth and smaller maxillary
and dentary teeth.  All had serrations and constricted roots and there seems
no reason to believe a beak was present.

David Majavovic wrote-

> AFAIK they had much less and much smaller teeth.

Pelecanimimus has seven premaxillary, about 30 maxillary and about 75
dentary teeth.  The maxillary teeth end before the antorbital fossa, while
the dentary teeth extend much further back to the anterior portion of the
antorbital fenestra.  Shuvuuia has an unknown amount of premaxillary (the
dentigerous margin is not preserved, but I don't think more than five could
have fit), about 25 maxillary and about 30 dentary teeth.  The maxillary
teeth extended almost to the antorbital fenestra and the dentary teeth ended
slightly anterior to them.  The teeth of Shuvuuia look larger than
Pelecanimimus, but I don't think there was much room for a maxillary beak,
as the later is supposed to have.

Mickey Mortimer