Diceratops and Torosaurus (was: Aquatic Dinosaurs)

["Tim Williams" <T.Williams@cclru.randwick.unsw.edu.au>]

 From Stan Friesen

> This produces a fairly interesting chain:
>     basal Torosaurus => Diceratops => T. horridus => T. prorsus


Except that Torosaurus has an extraordinarily long frill, and 
Diceratops and Triceratops both have short frills.  Is it possible 
that Torosaurus and Diceratops both evolved from a common ancestor 
which had a medium-length frill - Arrhinoceratops maybe.

Tim Williams