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Re: Dinosaur diversity

If it ain't broke, don't fix it!!!  There may not have been much ecologic
pressure fueling a dynamic change. If one accepts the punctuated equilibrium
dynamic for evolution, that would account for the changes we do see. However,
nothing succeeds like success. Certainly the types of numerous short-term
substantial climatic changes that characterize the last several million years
seem to be absent from the period of dinosaurian dominance.  What changes
there were in world-wide landmass reorganization are slow and gradual
compared to th emore recent models of continental glacial growth and retreat.

It has been some years since I was up to speed on paleoclimatology (having
learned what little I know at the knee of Ried Bryson at the U of Wis). It
would seem that until the forecast included a chance of meteor impact the
impetus for change were slow and gradual and certainly within easy and simple
adaptation.  Climatic zones did not expand to change entire continental
climates eliminating previously wide-spread climate types from a continent as
seems to have been the case for North America and Europe during the glacial

Just passing thoughts...

John Ellingson
At the edge of the Pleistocene in Madison, WI