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Re: The timing of stegosaur extinction



Tim Donovan wrote-

> So where else is Dsungaripterus known from besides
> the Tugulu Group?

 Gurvan Eran, Tevsh, Undurukhin and Tsagantsab
formations of Mongolia. I don't know in which of those
units or what other fossils show equivalence, though
Tugulu turtles "seem little changed from the late
Jurassic."

The only dsungaripterid Unwin and Bakhurina (2000) report from anywhere in Mongolia is "Phobetor" parvus, which was previously named Dsungaripterus parvus. This does not mean it can be used to correlate stratigraphy with Dsungaripterus weii though.
Your turtle statement is too vague to be useful.


> >K-Ar dating etc indicates a
> >Berriasian-Valanginian age for the Mongolian beds.
>
> Berriasian-Aptian, according to dates in Shuvalov
> (2000) for the Tsagantsav
> Svita.  Not very precise...


See pages 259 and 271. He made it clear that the Tsagantsav svita is dated at Berriasian-Valanginian on the basis of K-Ar dating and fossils. Also that Tsagantsabian deposition began before the end of the late Jurassic.

Ah, but his table 14.2 includes absolute dates which are as recent as Aptian (e.g. upper part of Tsagantsav Svita 120 +/- 5 Ma). The Aptian started 125 Ma (Gradstein and Ogg, 2004).


> >  IIRC K. Carpenter mentioned a new, Aptian age for
> the
> >Yellow Cat onlist.
>
> Where?  A search for "Carpenter" "Aptian" Yellow
> Cat" came up with no
> relevent posts.

  I just relocated it myself and will forward it to
you. I see the Yellow Cat could be either Barremian or
Aptian. If it is Barremian the NA stegosaurs
apparently disappeared before then.

I await this forwarded post.

Mickey Mortimer