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Re: tweet-tweet



On Sun, Apr 13, 2008 at 8:20 PM,  <hammeris1@bellsouth.net> wrote:
>
> But, to date, have they officially made birds a classification of dinosaur?
>  Or will they remain in their own order as close kin?

There's no official body which could do such a thing. The ICZN does
not cover taxa above the rank of family. Even if it did, it never
mandates the content of any taxon it covers (except that the type
specimen or subtaxon must be included).

The PhyloCode will cover such taxonomic names as "Dinosauria". I
mentioned Recommendation 11A in a previous post. Here's the link
again, for convenience:

   http://www.ohiou.edu/phylocode/art11.html#rec11a

I think it is likely that "Dinosauria" will receive a definition along
these lines under the PhyloCode: "the last common ancestor of
_Megalosaurus bucklandi_ von Meyer 1832, _Iguanodon bernissartensis_
Boulenger in Beneden 1881, and _Hylaeosaurus armatus_ Mantell 1833,
and all descendants of that ancestor."

In that case, birds would not "officially" be part of _Dinosauria_.
The only official dinosaurs would be the species mentioned above (or,
more precisely, the organisms represented by their type specimens).
But, of course, that does not mean there wouldn't be any other
dinosaurs. We can infer from various lines of evidence that
carnosaurs, coelurosaurs (including birds), ceratosaurs,
sauropodomorphs, stegosaurs, ceratopsians, etc. are descended from the
last common ancestor of _M. bucklandi_, _I. bernissartensis_, and _H.
armatus_. As such, they would also be considered part of _Dinosauria_.

Under this type of nomenclature, called "phylogenetic nomenclature",
_Aves_ would be considered a subclade of _Dinosauria_, just as
_Chiroptera_ is a subclade of _Mammalia_. Arbitrary ranks like
"Order", "Family", etc. are not necessary (or, IMHO, particularly
useful).

-- 
T. Michael Keesey
Director of Technology
Exopolis, Inc.
2894 Rowena Avenue Ste. B
Los Angeles, California 90039
http://exopolis.com/
--
http://3lbmonkeybrain.blogspot.com/