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Re: ADV: Re: Classification: A Definition
On Wed, May 16, 2007 at 06:35:46PM +0100, Mike Taylor scripsit:
> No, no, _alpha_ taxonomy, the naming of species and genera. Those we
> will never get rid of.
I am uncertain of that.
Specifically in paleontology, it's unclear that species level resolution
is possible at all, never mind generally, so the question ought to be
pretty much moot.
In biology, it doesn't strike me as genera are any less artificial than
families or orders, or that the "epithet <namer> <date>" style of
species reference wouldn't work at least as well.
> 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.
I am unclear how the designation of a species doesn't constitute a
phylogenitic hypothesis. So why are species and genera special?
Serious question; I don't see the scientific value in maintaining that
> > 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.
Not for an individual book that's trying to document a particular
hypothesis -- some specific tree -- it's not. If you're not trying to
do that -- this isn't an overview of dinosauria, it's a discussion of
some particular subset of dinosaurian clades, agreed, that's not the way
you'd want to go because you're ignoring the scale at which that
structure is present.
If what you're trying to do is to describe some particular clade or
clades, then there are other possible organizations; the specific
diagnostic features of the clade and its subclades come to mind.
> ... 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.
What I'm unclear on is the necessity of nominating some clade as "more
well-known"; I mean, yes, certainly, a clade that's received a lot of
study based on hundreds of specimens is better known than one based on
two fragmentary specimens and a single paper, but that is not a stable
state of difference. (Since in principle someone can always find more
specimens and more work can always be done.)
> > [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.
Some sort of substitution macro mechanism like end notes will probably
be used for all the references after the first one, yeah. But there are
lots of examples from the humanities of different ways to solve