Dinosaur beaks

["Aspidel" <aspidel@wanadoo.be>]

Hi all,

Stuff like some marvellous HP Luis Rey's paintings recently made an
interesting discussion on a paleo message board.
The question was: WHICH DINOSAURS HAD BEAKS? (it's obvious for most avian
dinosaurs).

- Coelurosaurs:

Which are the features of the premaxilla and/or the dentary that suggest
some coelurosaurs had beaks, especially:
     Caudipteryx
     advanced oviraptorosaurs
     Jeholornis
     Liaoxiornis  (...)
which I personnally restore with a beak. The lack of teeth? Other
characters?

Are there features which suggest the presence (or the absence) of a beak in
critters like e.g.:
     Archaeopteryx
     Microraptor
     Velociraptor
     Saurornithoides
     Sinovenator   ... etc ... ?

- Ornithischians:

IIRC remains of a fossilized horny beak has been found on at least 1
hadrosaur skull.
Has a fossilized horny beak been found in "hypsilophodonts", ceratopsians,
thyreophorans.... ?

Thanks in advance.

Cheers - Aspidel.