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On Mon, 5 Oct 1998, Betty Cunningham wrote:
> ok, we probably been over this (on the list) in the past-but... why the
> 'most recent common ancestor of _Triceratops_
(and modern birds)
> " equaling Dinosauria?? Why not Igunanodon as it's historical
> connection as first named Dinosaur? Was this picked from a hat or was
> there a better reason?
Ask Gauthier -- he was the first to cladistically define Dinosauria. Some
have suggested that _Megalosaurus_ and _Iguanodon_ would be more proper
anchors (although the clade would be exactly the same by standard
phylogenies), but Gauthier's definition has priority.
I think it had to do with traditional views on which is the most
"advanced" of the two lineages. Typically you see birds at one end of a
cladogram and ceratopsians at the other. Kind of arbitrary, yes.
--T. Mike Keesey <email@example.com>
DINOSAUR WEB PAGES -- http://www.gl.umbc.edu/~tkeese1/dinosaur/index.htm