Re: Fastovsky vs Archibald

[Tim Donovan <uwrk2@yahoo.com>]

--- David Marjanovic <david.marjanovic@gmx.at> wrote:

 

> What if a north-south temperature gradient --
> Alberta seems to have been 
> noticeably cooler than Wyoming in Hell Creek times
> -- played a role? 


  There were many lambeosaurs and saurolophines in
Alberta in the Campanian and early Maastrichtian, and
both forms radiated across the Bering area in that
period.




> This way 
> it is, for example, imaginable that certain species
> lived on the coastal 
> plain but _between_ the rivers. 

 I think that would be more likely in the wetter
habitats. Hadrosaurs were quite big and had to come to
the rivers for water, especially in times of drought,
which caused mass mortality. Consider the variety of
hadrosaurs preserved in Tsagayan and NA Campanian
units. Contrast that with younger Nemegtian and
Lancian beds. Hadrosaur diversity appears to have
declined steadily from the late Campanian to the
latest Maastrichtian. 






                
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