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Re: PRIORITY RULES



In a message dated 97-05-29 11:34:29 EDT, dwn194@soton.ac.uk (Darren Naish)
writes:

<< Wagner and I have been having an all-out email war over use of the terms
Aves
 and Avialae. He says Avialae should be used because of priority, but I said
that
 priority rules don't go for higher taxa, PLUS 'Aves' is just a tad older
than
 'Avialae' (like, more than 230 years older..). But _he_ says that, under the
new
 clad-rules, priority goes for whichever term was first published in a
 phylogenetic context (i.e. defined in a cladistic framework) _and_ these
 priority rules apply to all taxon names.  >>

These "new" clad-rules have not been ratified by any international body
recognized by or representing zoologists or biologists. They are nothing more
than conventions adopted by cladists in their works. I will spare the list
members my opinion of this particular attempt by cladists to take over
zoological nomenclature without due process...

HOWEVER--

Formally, the ICZN does not rule on taxa above the family level, so it's
anything goes. Every zoologist can have his or her own definitions of Aves
and Avialae, or can even give his or her own names to these groups. The
problem then becomes having >other< scientists accept the new names.

My own take is that Aves includes all theropod groups (my definition of Aves
is stem-based: all dinosaurs more closely related to _Megalosaurus_ than to
_Iguanodon_; Aves is the oldest available name for any group in this clade
and can readily be extended to encompass the entire clade), and that Avialae
is just another theropod suprafamilial subgroup of Aves (Avialae = common
ancestor of _Archaeopteryx_ and _Turdus migratorius_ plus all its
descendants; node-based definition), like Ornithomimosauria,
Deinonychosauria, Tyrannosauria, and so forth. As I've said before on this
list, not everything cladists have come up with is fatuous, and the idea that
defining taxa by descent is preferable to using characters has considerable
merit. I'm rewriting MM #2 third edition to refer to existing phylogenetic
definitions of dinosaur taxa and to provide such definitions for taxa that
don't already have them, with due regard for nomenclatural priority, of
course.