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Re: Classification: A Definition



Graydon writes:
 > On Wed, May 16, 2007 at 12:21:59PM +0100, Mike Taylor scripsit:
 > > Botterweg, Ronald (R.B.) writes:
 > 
 > [snip -- this is Mike, not Ronald]
 > 
 > > And that is why I cordially disagree with David Marjanovic's claim
 > > that PN makes taxonomy obsolete.  We'll always need alpha taxonomy.
 > 
 > Why?
 > 
 > I don't see what we get from families or orders that we can't get from
 > clade names;

No, no, _alpha_ taxonomy, the naming of species and genera.  Those we
will never get rid of.  Above that level I am broadly in agreement
that the ranks do more harm than good -- which should not particularly
suprising given that most of what little there is of my publishing
record is on rank-free phylogenetic nomenclature.

 > "Maniraptora" the clade is a perfectly good chapter heading, index
 > entry, and term of reference, even if it's "Maniraptora <cited
 > definer> <date>" rather than "Family Maniraptora", isn't it?

Yes.  No-one to disagree with here, move along.

 > >  > For example, besides the two mentioned amphibia websites, large
 > >  > standard works (just a few that I happen to know and use) such as
 > >  > Wilson & Reeder Mammal Species of the World and Walker's Mammals of
 > >  > the World, would become very impractical, loosing overview without
 > >  > classification in orders, families, etc.
 > > 
 > > A courageous approach would be to do away with chapters completely,
 > > and just order the entries according to a pre-order depth-first
 > > traversal of the hypothesised phylogeny.  But here I am using the word
 > > "courageous" in the Sir Humphrey Appleby sense :-)
 > 
 > Oh, piff -- I may not know much about dinosaurs, relatively speaking,
 > but I know lots about structuring information.  You can perfectly well
 > pick a phylogentic hypothesis, pick the resulting representative tree,
 > pick a sibling-level slice through the children of that tree some number
 > of levels down from the root, and use those clade names as your chapter
 > headings if you want to.  It's actually *easier* from an information
 > design point of view to structure a book that way than by arbitrary
 > buckets labelled families.

The buckets would still be arbitrary, dependent to a ludicrously
unstable degree on the taxon selection.  Throw another basal sauropod
in there and Neosauropoda is suddenly eleven nodes down from the root
instead of ten, and the hypothetical chapter-headings scheme in which
we use the level-ten nodes suddenly leaves with no Neosauropoda
chapter but with an unexciting
Node-uniting-Lourinhasaurus-with-Neosauroda chapter.  Picking an
arbitrary level is also a horrible way to go -- which is why
_Dinosauria_ 2nd ed. does what everyone sane would have expected it
to do, and uses chapter headings based on the "well-known" clades.

... but as soon as you've nominated some clades as more well-known
than others, you've done taxonomy.  We may as well admit it to
ourselves.  It's certainly true that PN requires us to do much _less_
taxonomy than previously, but it doesn't eliminate it.

 > [snip]
 > > I truly don't know.  It certainly is awfully hard to resist them
 > > tempatation to write things like "... and so representatives of at
 > > least four sauropod families are known from the Wealden".  And
 > > changing that to "at least four clades" only makes things worse.
 > 
 > "Representatives of the sauropod clades <clade name> <cited
 > definer> <date>, .... are known from the Wealden" strikes me as
 > much more useful.  Even the angiosperm worker knows what they've
 > got and where to look up the definitions.

That works.  It gets cumbersome pretty quickly, though.

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor    <mike@indexdata.com>    http://www.miketaylor.org.uk
)_v__/\  "I never comment on referees and I'm not going to break the habit
         of a lifetime for that prat" -- Ron Atkinson, after WBA's UEFA
         Cup defeat to Red Star Belgrade.