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Re: A Clutter of Duckbills



>From: RaptorRKC@aol.com
 > 
 > Hypacrosaurus, Corythosaurus, and Lambeosaurus, for example.  Without the
 > crests, it is rather hard distinguishing one animal from the other. ...
 >
 >  What details keep this lump of animals in different genera? 

In these it is almost entirely the crests.  I agree that this is
probably not a sufficient basis for separate genera.
 
 > Hypacrosaurus and Corythosaurus have the same type of crest, the
 > "helmet" crest, and Lambeosaurus has a similar crest except that the
 > lambeosaurus crest has a thin spine sticking backwards on it. 

Actually, the official difference is that the crest of Lambeosaurus
slopes forward, while that of Corythosaurus slopes backwards (Note,
the second species of Lambeosaurus does NOT have a backwards oriented
spike).
 
 > Stanley Friesen suggested to me that all of the species of these
 > three genera may actually belong to only one genus -- ...

What do the readers here think?  Should I go ahead an lu,p them in
my dinosaur list?  Right now I am being conservative on this, but
I am not entirely comfortable with these as separate genera..
 > 
 > Another group of hadrosaurs that confuse me are Gryposaurus, Hadrosaurus,
 > Kritosaurus, and Brachylophosaurus. 

I currently *am* treating Hadrosaurus, Kritosaurus and Gryposaurus as
a single genus (Hadrosaurus, of course).

 > Just what keeps two species in the same genus?  And just what keeps them
 > separate?

Consensus :-)

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.