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Re: Theropod "migrations"
In a message dated 4/24/99 2:03:38 AM EST, email@example.com writes:
<< And *Saurolophus* is the only real single genus of
herbivore that crossed the Berring bridge.
*Brachiosaurus,* *Barosaurus,* and possibly
*Pleurocoelus* may have gone the Eurasian way, popped
into Africa before that bridge broke off. >>
I've compared the two species of Saurolophus, and there are enough
differences between the two--both cranially and postcranially--that the
Mongolian species certainly belongs in its own genus. Both are saurolophines,
but each must have evolved its crest independently (they don't use quite the
same skull bones for their crests, for example); Saurolophus osborni is
probably a direct descendant of a species of Prosaurolophus, while
Saurolophus angustirostris descended from some as yet unknown Mongolian
saurolophine. One of these days I'll have to publish this stuff and give
Saurolophus angustirostris its own new generic name (already have one in
mind). The two crested saurolophines aren't so closely related that one must
have descended from the other (or both from a very close crested common
ancestor), and so there is again no need to pretend that Saurolophus itself
somehow crossed from Asia to America (or vice versa) to give us the same
genus in both regions.