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Tom Holtz wrote:
<<Again, be not so hasty in assuming these particular taxa are the ones
chosen.  The "anchor taxon" for Ornithopoda has not been explicitly named as
of yet, and I personally would like to see _Iguanodon_ get its due (i.e.,
Ornithopoda = _Triceratops_ > _Iguanodon_; Euornithopoda = _Hypsilphodon_ +
_Iguanodon_; etc.)>>

Well, besides the reasons that George mentioned, ie that _Iguanodon_ could
become a nomen dubium (ACK!!!), I used _Lambeosaurus_ because there are more
ornithischian clades that are inclusive of _Lambeosaurus_ than _Iguanodon_.
 _Igunodon_, as far as modern cladistics sees it, forms an exclusive clade
with the Asian big-nosed as-of-yet-unnamed taxon popularly (but utterly
incorrectly) refered to as _"Iguanodon" orientalis_.  Then it is the outgroup
to _Ouranosaurus_, _Probactrosaurus_, lambeosaurids, and saurolophids
together.  My point for using _Lambeosaurus_ is for the consistant name in
defining ornithopod taxa, rather than using _Iguanodon_ 'til you get to
Iguanodontoidea and Iguanodontidae, and then using _Lambeosaurus_ for the
rest.  Actually, if anyone cares, since Sereno didn't (and still hasn't)
given any of his taxa explicit cladistic definitions, I have given them some:

Ornithischia {Triceratops > Passeres | Diplodocus | Plateosaurus}
Predentata {Pisanosaurus + Lesothosaurus + Triceratops}
Genasauria {Stegosaurus + Ankylosaurus + Triceratops}
Thyreophora {Stegosaurus > Triceratops}
Cerapoda/Neornithiscia {Triceratops + Lambeosaurus}
Marginocephalia {Triceratops > Lambeosaurus}
Ornithopoda {Lambeosaurus > Triceratops}
Pachycephalosauria {Pachycephalosaurus > Triceratops}
Ceratopia {Triceratops > Pachycephalosaurus}
Neoceratopia {Triceratops > Psitticosaurus}
Euornithopoda {Hypsilophodon + Lambeosaurus}
Iguanodontia {Lambeosaurus > Hypsilophodon}
Euiguanodontia {Gaspirinisaura + Lambeosaurus}
Dryomorpha {Dryosaurus + Lambeosaurus}
Ankylopollexia {Camptosaurus + Lambeosaurus}
Iguanodontoidea {Iguanodon + Lambeosaurus}
Hadrosauroidea {Ouranosaurus + Lambeosaurus}
Hadrosauria {Saurolophus + Lambeosaurus}
Saurolophidae {Saurolophus > Lambeosaurus}
Lambeosauridae {Lambeosaurus > Saurolophus}

This, of course, is based on the notion that _Hadrosaurus_ is undiagnostic
beyond the point of falling somewhere in the clade of animals closer to
_Saurolophus_ than _Lambeosaurus_.  Unless someone can go to New Jersey and
dig up a head of this thing and demonstrate beyond any resonable doubt that
it belongs to the same kind of animal as the original _Hadrosaurus_ skeleton,
it will almost certainly have to become a nomen dubium.

Anyways, that is why I used _Lambeosaurus_ instead of _Iguanodon_.

Peter Buchholz

PS, I have tried to email Sereno concerning the apperent synonymy of Cerapoda
with Neornithischia, as of yet there is no reply, but I will keep you posted
when/if he does.