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Re: Everything you know about the Iren Dabasu age is wrong...

On Sun, 25 Sep 2005 02:45:42 -0700 (PDT) Tim Donovan <uwrk2@yahoo.com>
> --- "Jaime A. Headden" <qilongia@yahoo.com> wrote:

> >   This is like arguing that if we find a tyrannosaur
> > in one Maastrichtian
> > environment, it must be in ALL formations of that
> > age without variance. 
>  No. If Mesolanistes is found from North America all
> the way to southern China (I presume Shuvalov meant
> the Maastrichtian Pinging formation)it should be
> present between these regions,

It doesn't have to be present in the areas between the localities. 
Different paleoenvironmental conditions can create huge geographic gaps
in the range of snails.

> and it is known from
> the Nemegt. If Iren Dabasu
> were really of Nemegtian
> age, Mesolanistes should be
> present there too(the
> paleoenvironments were
> similar).

Paleo drainage patterns may have limited the spread of Mesolanistes into
new areas.  Besides, it is probably unwise to base such sweeping
generalizations on the occurrence or absence of one taxon.

What does the palynology of these localities indicate?