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Padian et al. 1999 (Was: New PaleoBios paper - diplodocoid phylogenetic taxonomy)

> Date: Tue, 04 Oct 2005 11:12:35 -0300
> From: Roberto Takata <rmtakata@gmail.com>
> Sender: owner-dinosaur@usc.edu
>>         Padian, K., J. R. Hutchinson and T. R. Holtz, Jr.  1999.
>>         Phylogenetic definitions and nomenclature of the major
>>         taxonomic categories of the carnivorous Dinosauria
>>         (Theropoda).  Journal of Vertebrate Paleontology 19:69-80.
> Isn't this paper criticized by Sereno? I not sure if he did that in
> the 'A rational for dinosaurian taxonomy' (1999 JVP 19: 788-90).

I don't know, I don't have that one.  But I do know that he doesn't
even cite Padian et al. 1999 in --

        Sereno, Paul C.  1999.  Definitions in phylogenetic
        taxonomy: Critique and rationale.  Systematic Biology,
        48: 329-351.

Anyway -- just because Sereno criticises something doesn't make it
bad!  :-)

> (It's ofen said that a clade or a node-based definition is more
> stable than a apomorphic or a content list based definition, it
> seems that it not actually true.)

(Bit of a non-sequiteur there?)

Nodes and stems may not be more _stable_ than apomorphy-based clades,
but they are more explicit, and that may be more important.  They
depend only on the topology of the phylogenetic hypothesis, whereas
apomorphy-based clades also depend on the distribution/optimisation of
character transitions.

By the way, I think the word "stable" is asking for trouble in
discussing approaches to classification.  A lot of the 1990s papers
both for and against phylogenetic taxonomy advocated their preferred
system on the basis that is was "more stable" than the alternative,
and it's apparent that the authors were using the word in completely
different ways.  Phylogenetic taxonomy maintains stability of
definition at the expense of stability of content; traditional
("Linnaean") taxonomy does the converse.  So I always try to be
explicit about whether I mean stability of content or of definition.

(And the goal, of course, is to craft phylogenetic definitions of
clades which remain as stable as possible even as phylogenetic
hypotheses change.  That's why I don't want to see a definition of
Mamenchisauridae any time soon -- the topology is so unresolved that
it's just not possible to make a definition that maintains any
stability at all in content.)

[Sorry if all that was a bit patronising.]

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor  <mike@miketaylor.org.uk>  http://www.miketaylor.org.uk
)_v__/\  "``IMHO'' is only four keystrokes" -- Dave Foreman.