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RE: the last stegosaur

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Tim Donovan
> Which stegosaur was the youngest? Wuerhosaurus was of
> Tsagantsabian age, and
> may have been pre-Barremian. I notice stegosaurs were not included in the
> faunal list for the Mazongshan unit of Barremian age. But
> Katsuyamakensaurus is supposedly of Barremian-Aptian age.  Is
> that cerdible?

Given that no material has yet to be published, described, and even (as far
as I can remember) even photographed and put on the web concerning the
informal taxon "Katsuyamenryu" (aka "Katsuyamekensaurus"), it has
(currently) unverifiable credibility...  Furthermore, if (for example) this
was based soley on teeth, or on isolated conical plates, it could very well
be something other than a stegosaur.

Ah, the joys of using the web as a primary resource... :-S

>   Wuerhosaurus was once considered as young as Albian. I also note
> stegosaurs seem extirpated by the Barremian in America.

In answer to your question, though, Wuerhosaurus was once considered to be
the latest-occuring stegosaur, but new (as you note) new data indicate that
it could be older than the Wealden stegosaur material.  The Katsuya material
may, or may not, be stegosaur, but (as with its morphology) its stratigraphy
is not yet published. (Early Cretaceous units in Japan represent quite a big
chunk of time).

So (depending on the precise age of Wuerhosaurus), either that Asian form or
the Wealden taxa  or the problematic (age and morphology) Monokosaurus of
Tibet or various possibly stegosaurian trackways may be the youngest known
indication of Stegosauria.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796