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Re: Tyrannosaur Evolution



----- Original Message -----
From: "Tim Donovan" <uwrk2@yahoo.com>
Sent: Monday, February 14, 2005 12:31 PM

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

All maps give this impression. The only mountain range should have been the Appalachians (...and perhaps the Ozark mountains).


 Possible? Definitely. Compare T. rex and
Dryptosaurus. The latter seems a frozen relic of the
pre-Baynshirenian stage of tyrannosaur evolution.

The east lacked big ceratopsids etc.

While this is probable (tyrannosaurids and ceratopsids seem to have evolved in Asiamerica and would have needed to cross a sea...), are you sure you aren't confusing absence of evidence and evidence of absence here?


Note that Saurolophus, an American immigrant,
seems well adapted to the predator.

How do you mean?