Re: Ornithomimid beaks

["T. Mike Keesey" <tmk@dinosauricon.com>]

On Sat, 1 Sep 2001, Graydon wrote:

> I meant to ask, 'in theropods, how many times did beaks evolve?'; it's
> obvious that there are many beaked things (squid, turtles,
> dicynodonts...) and it's obvious that there have been beaks more than
> once in the dinosauria (ornithsichians and aves), but so far as I know
> it's *not* obvious how many times beaks came up in theropods, or whether
> they're a synomorphy for the clade that has Aves in it, or if some
> *type* of beak is.

Beaks appear to have evolved at least three times within _Theropoda_ (all
within _Maniraptoriformes_): once in _Ornithomimosauria_, once in
Clade(_Oviraptor_ <-- _Passer_) (which includes _Therizinosauria_), and
once within _Aves_. It is not certain whether _Avimimidae_ and
_Alvarezsauria_ belong to one of these groups or evolved beaks
independently.

Toothlessness evolved within each of the three aforementioned clades, once
in _Ornithomimidae_, once in Clade(_Oviraptor_ <-- _Therizinosaurus_), and
at least three times within _Aves_ (within _Confuciusornithidae_,
_Enantiornithes_, and _Carinatae_).

_Shuvosaurus_ may be a toothless basal theropod. Is it supposed to have
had a beak?

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