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Re: NON-ORNITHOPOD AGILISAURUS
> I have long maintained that small ornithischians are probably divisible into
> small unspecialized ornithopods, small unspecialized marginocephalians, and
> so forth, but poor quality of remains makes them difficult to separate.
As noted by Drs Maryanska and Osmolska, pre-Cretaceous
marginocephalians may be so "unspecialized" as to be unrecognisable as
basal members of the Marginocephalia rather than as "fabrosaurs" or
"hypsilophodonts" or whatever.
Take _Psittacosaurus_ - its skull may be highly evolved, but
its postcranium is quite unspecialised, especially for an
ornithischian of the Cretaceous. It wasn't even very cursorial.
There's a few derived features in the hips, and some psittacosaur
specimens show ossified tendons; but overall, the postcranial
elements of _Psittacosaurus_ are more typical of a lower Jurassic