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Re: Formal definition of the Dinosauria
Jeff Poling wrote:
> While arguing with the author of Ask Shagg over the proper definition
>of a dinosaur (the guy used an english dictionary, rather than a natural
>history text) I realized my article called "Dinosauria defined" does NOT
>have the definition of dinosauria. It has Gauthier's 1986 definition of
>Saurischia and Padian's 1993 definition of Ornithischia, but not a
>similar definition for Dinosauria.
> So whut is the "official" definition of dinosauria?
The definition of Dinosauria is something you can get into public debates
Under phylogenetic taxonomy, Dinosauria = all descendants of the most recent
common ancestor of _Triceratops_ and modern birds (Holtz & Padian, 1995, and
in prep.), with Ornithischia = all taxa sharing a more recent common ancestor
with _Triceratops_ than with Saurischia (Padian & May, 1993) and Saurischia =
all taxa sharing a more recent common ancestor with birds than with
Ornithischia (Gauthier, 1986).
When I suggested how much nicer things would have been if they had used
_Iguanodon_ instead of _Triceratops_ and _Megalosaurus_ instead of modern
birds, they thought it was a great idea. Unfortunately, under the
principles of phylogenetic taxonomy, the first definition of a taxon under
those rules has priority. Oh, well.
Thomas R. Holtz, Jr.
Vertebrate Paleontologist Webpage: http://www.geol.umd.edu
Dept. of Geology Email:email@example.com
University of Maryland Phone:301-405-4084
College Park, MD 20742 Fax: 301-314-9661
"There are some who call me... Tim."
-- Tim the Enchanter, "Monty Python and Quest for the Holy Grail"
"Tim?!? They called me TIM?!?!"
-- me, on seeing the credits to "The Ultimate Guide to T. rex" :-)