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Re: Tyrannosaur Evolution

>  Some maps give the impression the east was mostly
> flat, with little or no mountain building or
> intermontane basins conducive to isolation and
> speciation.

Not to speak ill of Ernst Mayr's intellectual progeny, (since he just passed 
away and all), but geographic isolation is likely NOT necessary for speciation 
events.  The genetics of speciation due to geographic isolation are easier to 
grasp (especially with a significant founder effect), and much easier to model 
mathematically, which is probably why it caught on first, but there are reams 
of papers and entire publications dedicated to alternate models of speciation, 
due to selective gradients, selective change across boundary conditions (i.e. 
edge-effects), genetic drift, behavioral reinforcement of reproductive 
isolation, etc.  So don't jump to any phylogenetic conclusions based on limited 
assumptions about speciation models.

A good overview can be found in Jerry Coyne's recent book, cleverly titled 

Scott Hartman
Zoology & Physiology
University of Wyoming
Laramie, WY 82070

(307) 742-3799