Re: Theropod "migrations"

[Dinogeorge@aol.com]

In a message dated 4/24/99 2:03:38 AM EST, qilongia@yahoo.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.