Re: Nemegtian tyrannosaurs

["Jaime A. Headden" <qilongia@yahoo.com>]

Tim Donovan (uwrk@yahoo.com) wrote:

<The Nemegt is not that old, and it was relatively dry. Based on studies
at Bugin Tsav, members of the JMJPE recently concluded the climate was
often "very dry during the Nemegt Age." The Nemegt and Barun Goyot
actually have an interfingering relationship i.e. the desert was never
very far and occasionally encroached on Nemegtian territory. This was
recently determined at Hermiin Tsav and is also very obvious at Red
Walls.>

  The Bugin Tsav was partially Barungoyotian, however, as was Khermeyin
Tsav, not only Nemegtian. Studies at the type locality of the Nemegt
Formation, Nemegt (Nemegetu), show a much more fluviatile, swamp-like
environment, much as in the Dinosaur Park Formation. Tom Holtz rightfully
points out that Retallack has drawn these variables. As for an
interfingering relationship between the Nemegt and Barun Goyot, this is as
far as I know unsupported, and I would be curious to know where this
evidence occurs. As far as I can tell, the contact between the two
formations occurs in only two sites, Bugin Tsav and Khermeyin Tsav (in
regards to the so-called White and Red Beds). 

  If you would, could you cite references to this interfingering?

  As for age, the Nemegt remains undefined as to wether it is wholy
Campanian (as the Dinosaur Park), straddling the boundary, or lower
Maastrichtian or even mid-Maastrichtian. The age varies by an large
degree, but generally the upper Campanian fits better faunistically, and
this is why I used the age of 75my, rather than younger.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

__________________________________
Do you Yahoo!?
Yahoo! Calendar - Free online calendar with sync to Outlook(TM).
http://calendar.yahoo.com