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Re: R: HETERODONTOSAURIDS AND BASAL CERAPOD PHYLOGENY
--On Tuesday, May 04, 1999, 12:46 PM +0200 "Alessandro Marisa"
> Perhaps, in this non-node Cerapoda on the Cerapoda can be included
> Agilisaurus louderbacki?
> I have a suspect that the traditionally placement of Agilisaurus as a
> Ornithischia at the same level of Lesothosaurus diagnosticus is errated,
> skull of Agilisaurus is more derived from that of Lesothosaurus in some
> features (es. five premaxillary teeth, absence of a maxillary fenestra).
> also the pelvis is more similar to that of Hypasilophodon than to
> Lesothosaurus (es. prepubic process, obturator foramen and obturator
I agree. _Agilisaurus_ appears much too derived to be a sister taxon to
_Lesothosaurus_. In looking at the pelves of many ornithopods, it strikes
me that only in this group do you consistently see the prepubic process
extend more cranially than the preacetabular process of the ilium. Only in
one or two stegosaurs is this condition even approached outside of
Ornithopoda (excluding heterodontosaurids, of course).