Re: Defining Ornithischia (was Re:)

[Mike Taylor <mike@indexdata.com>]

David Marjanovic writes:
 > > A phylogenetic definition would have to mention at least one
 > > organism, yes; but there are other kinds of definitions, and for
 > > most of the last 249 years, "key character"-based definitions
 > > were almost universally used.
 > 
 > They were often called "definitions", but that was always wrong. 

Again, I must disagree.  Any statement that defines one thing in terms
of others is a definition.  That's what the word means.  You can't
just hijack the word and make it mean what you want it to mean -- the
kind of definition that you happen to prefer.

 > [...] definitions are immutable under traditional nomenclature; the
 > diagnoses have never been, everyone is free to change them by
 > simply saying so in a publication.  (Witness the change of that of
 > Mammalia from "mammary glands" to "hair" to "secondary jaw joint"
 > to "fusion of prootic and opisthotic" or whatever the braincase
 > character was that turned the isolated braincase *Adelobasileus*
 > into the famous first mammal.)

So?  Witness all the changes in the phylogenetic definition of
Theropoda as chronicled at:
        http://www.taxonsearch.org/dev/taxon_edit.php?tax_id=310&Action=View

That doesn't stop any of them from being definitions.

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor    <mike@indexdata.com>    http://www.miketaylor.org.uk
)_v__/\  "One world, One web, One program" -- Microsoft Adversisement.
         "Ein Volk, Ein Reich, Ein Fuhrer" -- Adolf Hitler.  Coincidence?