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Re: TRICERATOPS AND PSITTACOSAURUS ARE NOT OVERSPLIT
----- Original Message -----
From: "Steve Brusatte" <firstname.lastname@example.org>
To: <Tetanurae@aol.com>; <email@example.com>
Sent: Wednesday, March 07, 2001 11:42 PM
Subject: Re: TRICERATOPS AND PSITTACOSAURUS ARE NOT OVERSPLIT
> All over the place in Asia, yes. Mostly northern China and Mongolia, as
Peter said, but there >is also P. sattayaraki from Thailand (which is so
fragmentary...has this one been debunked >yet?). However, northern China
and Mongolia, although very, very large, is still the same >general area.
Now, we only need more stratigraphy and temporal data, which is always hard
to >come by.
In regard to the species Psittacosaurus sattayaraki, in his article on
Marginocephalia published in the book "The Age of Dinosaurs in Russia and
Mongolia" Sereno referred P. sattayaraki as a Ceratopsia, incertae sedis, on
the basis that all Ceratopsia have short, deep dentary rami, and the primary
ridge on the dentary teeth of P. sattayaraki, such as it is preserved is not
bulbous as in Psittacosaurus; the dentary flange present in P. sattayaraki
is develops only in some Psittacosaurids (es. P. mongoliensis and P.
meileyingensis) and extend vertically as a ridge across the posterior
portion of the ramus, unlike the dentary of P. sattayaraki. The unusual
features of the P. sattayaraki's dentary is the low position of the
predentary attachment surface relative to the teeth row and the medial
arching of the symphyseal region of the dentary. The anterior part of the
dentary appears unfinished, bringing into question its interpretation as a
broad attachment area for the predentary.
Sereno also considered the species Psittacosaurus mazongshanensis as a nomen
nudum on the base that there are no clear diagnostic features that are
absent in other Psittacosaurus species.
In view of this Sereno included the following species in the genus
Psittacosaurus: P. mongoliensis, P. sinensis, P. xinjiangensis, P.
meileyingensis, P. neimongoliensis and P. ordosensis.
"Volounteer of Paleontological Museum of Monfalcone"
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