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Re: Revised Ornithischian Classification



Jaime Headden wrote-

>   Gasparinisaura does not jump around in cladograms a lot ... it
> stays just outside of Dryomorpha, always has since 1996 when
> described and included....

In how many analyses now?  I don't keep up with the ornithischian literature
much, but it seems to me that Gasparinisaura has only been included in _one_
published phylogenetic analysis.  This was Coria and Salgado's, when it was
first described.  This analysis only contained Hypsilophodontidae,
Tenontosaurus, Gasparinisaura, Dryosauridae and Ankylopollexia as ornithopod
OTU's.  Does anyone realize just why Gasparinisaura is said to be more
derived than Tenontosaurus (in other words, what the Euiguanodontia is based
on)?  Four characters-
- jugal-postorbital articulation laterally faced.  If anyone understands
this character, please feel free to explain it.  In all ornithischians where
I can tell, the postorbital ventral process overlaps the jugal ascending
process laterally.
- lateral primary ridge on maxillary teeth present.  True, though I hear
Parksosaurus also has it.  It is lacking in rhabdomorphs.
- brevis shelf well-developed.  If only I had more dorsal/ventral views of
ornithopod ilia....
- metatarsal I reduced or absent.  True, though much more in Gasparinisaura
and Dryosaurus than Camptosaurus oddly.
Do I have any better idea of it's phylogenetic relationships?  No, but I
think more research with a larger taxon sample and more characters should be
performed until we conclude Gasparinisaura "always" stays as the sister
group to Dryomorpha.

Mickey Mortimer