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Re: The timing of stegosaur extinction



--- Michael Mortimer <mickey_mortimer111@msn.com>
wrote:

> Tim Donovan wrote-

> >  Dsungaripterus is also known from the
> Wuerhosaurus
> >bearing upper Tugulu group. Those beds are
> considered
> >the equivalent of Tsagantsabian beds in Mongolia
> based
> >on fossils.
> 
> 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."

> 
> >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.


> 
> >  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.

 Tim
> 
> 
> 


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