Also, I was under the impression that Psittacosaurs
were considered by some workers to not bee ancestral
to Neoceratopians,
_Psittacosaurus_ is the sister taxon to the Neoceratopsia. You're certainly
right in saying that it was not directly ancestral to neoceratopsians: as
well having derived characters that preclude it from being ancestral to
neoceratopsians, the genus _Psittacosaurus_ also lived too late in time.
But it (and _Chaoyangsaurus_) are the closest known relatives of the
neoceratopsians.
Hope that helps.
Tim
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