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RE: the last stegosaur

From: "Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>
To: <msdonovan66@hotmail.com>, <dinosaur@usc.edu>
Subject: RE: the last stegosaur
Date: Mon, 29 Jul 2002 09:32:21 -0400

> 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.

But is Wealden stegosaur material e.g. the Craterosaurus fragment, reworked? Also is the age of the Wealden well known? Is it Hauterivian or could it range frm Berriasian to Barremian?

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.

I once read that the unit that yielded Malawisaurus also yielded stegosaur material. When I asked about the age of this unit, somebody mentioned 115 Ma, if he remembred what Jacobs told him correctly. 115 Ma would be much younger than Paranthodon or any other definite stegosaur.

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

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