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Re: Age of the Barun Goyot, Djadoktha and Nemegt Formations
Speaking of Probactrosaurus, the exhibit of dinosaurs
from China currently on display at the Field Museum:
http://www.fieldmuseum.org/dinosaurdynasty/
Includes a skeleton of an iguanodontid which the
display material states is an unnamed genus similar to
Probactrosaurus. Does anyone know if a description of
this specimen will be out soon?
Guy Leahy
----------------------------------------------------
--- Tim Williams <twilliams_alpha@hotmail.com> wrote:
> Jaime Headden wrote:
>
> > But maybe I can counter Donovan's statement
> above by saying that someone
> >else
> >thinks that the two *Saurolophus* species are
> different genera? Researcher
> >vs.
> >researcher, who will win!? (While I'd bank on
> Norman for his credentials, I
> >and
> >others will note he tends to be a lumper and has
> dismissed variation in
> >geographic areas due to individual variation,
>
> Several ornithopod species that have been "lumped"
> in the same genus are
> currently in the process of being de-lumped (or
> should that be un-lumped?).
> (For example, one famous ornithopod genus is about
> to be pared down in
> dramatic fashion.) However, although Norman
> apparently has a reputation as
> a "lumper" (see above), he did recognize that
> _"Probactrosaurus"
> mazongshanensis_ does not belong in the genus
> _Probactrosaurus_ (among other
> features, the dentary tooth crowns of
> _mazonhshanensis_ more closely
> resemble those of _Altirhinus_ than _P. gobiensis_).
>
> Norman D.B. (2002). On Asian ornithopods
> (Dinosauria: Ornithischia). 4.
> _Probactrosaurus_ Rozhdestvensky, 1966. Zoological
> Journal of the Linnean
> Society 136: 113-144.
>
> And while certain parts of the euornithopod tree may
> be "lumpy", other parts
> may be oversplit when it comes to the number of
> genera. Just look at
> _Hypacrosaurus_, _Corythosaurus_ and _Lambeosaurus_,
> or _Edmontosaurus_ and
> _Anatotitan_. The same is pretty much true for
> advanced ceratopsids. The
> validity of genera often lies in the eye of the
> beholder, and so makes for a
> poor yardstick in biostratigraphy.
>
> Cheers
>
> Tim (not Donovan).
>
>
>