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Re: The timing of stegosaur extinction



--- Mickey Mortimer <Mickey_Mortimer111@msn.com>
wrote:

> 
> Early Cretaceous, Sand Wells Formation (USA),
> ?Stegosauridae indet..

   What is the age of that unit? Not long ago, there
was a report of Stegosaurus in Siberia, indicating a
connection with NA. In light of that, and the close
affinitiy of Stegosaurus and Wuerhosaurus, I think the
latter may have been present in NA early in the K. But
recently the Yellow Cat-lacking stegosaurs- has been
redated to c Aptian, indicating a very long gap
between the Morrison record and the first good early
Cretaceous record in NA. The Asian and NA records
suggest stegosaur extinction occurred before the
Aptian.


> 
> > SA: Early Cretaceous only. (The one fossil is
> still unnamed.)
> 
> Barremian, La Amarga Formation (Argentina),
> Stegosauria indet..

  Barremian? I thought it was Hauterivian.

> 
> > Africa: Late Jurassic only.
> 
> Berriasian-Valanginian, Upper Kirkwood Formation
> (South Africa), Paranthodon
> africanus.


  Didn't Russell mention possible stegosaur remains
from the late early Cretaceus of Morocco?


> 
> 
> Early Cretaceous, Potton Sands (England),
> Craterosaurus pottonensis.

  Wasn't that material reworked?

 
> 
> > Asia: Middle Jurassic to Early Cretaceous.
> 
> Valanginian-Albian, Tugulu Group (China),
> Wuerhosaurus homheni.
> Valanginian-Albian, Qaganur Formation (China),
> Stegosauria indet..
> Early Cretaceous, Ejinhoro Formation (China),
> Wuerhosaurus ordosensis.


  I think Wuerhosaurus was no younger than about
Valanginian. An Aptian-Albian age seems outdated and
dubious. Wuerhosaurus homheni was of Tsagantsabian
age, and Shuvalov wrote that Tsagantsabian sediments
had already begun to accumulate by the end of the
Jurassic. According to Lucas, W. ordosensis also
appears to be of Tsagantsabian age.


> 
> India
> 
> Maastrichtian, Kallenkurichi Formation,
> Stegosauridae indet..


  Didn't Galton and Upchurch recently resurrect
Dravidosaurus, considered by Chatterjee to be a
plesiosaur? I thought the Indian stegosaur was of c
Coniacian age.

  Tim




                
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