Classifications (was Platnick's view)

[Ken Kinman]

Dear All,
    First let me respond to Pierre Deleporte's suggestion, as I have thought
about this a long time (since he suggested it to me several years ago).
Perhaps the {{markers}} are not enough, and the "names" of paraphyletic
groups should be explicitly labelled as such.  Since they are only part (or
percentage) of an entire clade, I am going to propose labelling them with a
percentage symbol (%).  Amphibia% would indicate a singly paraphyletic group
(one exgroup, Amniota).  Reptilia%% would indicate a doubly paraphyletic
group (two separate exgroups, mammals and birds).
    He also brought up "feathers" as a significant synapomorphy, which I am
very much against.  Significant character gaps are those which clearly aid
in diagnosis and usually arose in a relatively short period of time.
Feathers not only fossilize poorly, but the transition from protofeathers to
vaned feathers was gradual and took a long time (even on a geological time
scale).  Furthermore, reversals to protofeather-like structures (kiwis being
a good example) further complicate such a character.
      The transition from a reptilian type of jaw-ossicle complex to the
mammalian jaw-ossicle complex happened more quickly, and reversals of such a
character complex would be extremely unlikely.  Mammals evolved from one
kind of reptile, birds evolved from another kind of reptile.  Restricting
the definition of Reptilia was cladistic smoke and mirrors, again triggered
by the idea that formal paraphyly is bad, unnatural, and a mistake.
    In response to Curtis.  "Information value" is a key theme of the Kinman
System.  The place-markers are a required element that lies at the very
heart of the system.  Such markers explicitly document that an exgroup has
been removed and the name of that exgroup.  By adding a marker for Amniota
within Class Amphibia, you explicitly show that Amphibia + Amniota is a
holophyletic group.  With the percentage sign convention proposed above, you
can easily label paraphyletic groups in text as well.  And by placing the
{{marker}} next to its sister group, the continuity of evolution is
documented within the classification.  Coding can add even more precision to
their relationship with other taxa.  The Kinman System does not fail the
"information value" test.
     Now for Thomas Pape's objection.  Class Amphibia, like all good formal
paraphyeltic groups, has a synapomorphy at its origination and another
synapomorphy where it is truncated.  In other words, you can define or
diagnosis it as "It has THIS, but not THAT."  An amphibian IS a tetrapod
that does NOT lay amniotic eggs.  Before amniotes evolved, Amphibia was a
perfectly good holophyletic group, and it's "naturalness" does not disappear
just because amniotes evolved from them.
       Where you want to draw the exact line for "tetrapod" or "amniote" is
unavoidably arbitrary whether you are an eclectist or a strict cladist.  But
you can minimize arbitrariness by picking significant gaps, and as I
discussed above, feathers don't seem to qualify.  Eclectists are just using
such major truncations as both the end of one taxon and the beginning of
another.   If this one additional criterion is required to head off a
nomenclatural disaster, I think it is well worth it.
     Strict cladists, instead of coming up with a simple convention (such as
my markers) took the other fork in the road.  They instead choose to store
holophyletic information in a more *simplistic* way, which actually ends up
making classifications increasingly more complicated as they grow.  It
reminds me a lot of combatting pests with toxic chemicals, or the overuse of
antibiotics.  They too were simplistic solutions, and in the long run they
didn't work well and ended up doing a lot of damage.
            ------ Ken Kinman

P.S.  In my book I referred to my {{markers}} as place-markers or
semi-paraphyletic markers.  In my correspondence since then, some people
have referred to them as Kinman markers.  Call them whatever you want, this
kind of cross-referencing marker is the key to the Kinman System, and I will
continue to criticize anyone who does not explicit mark paraphyletic groups
in this or some comparable way.  And if labelling paraphyletic taxon names
with something like a % sign makes it more acceptable, I'm all for it.
    It's not just the strict cladists I am criticizing.  I'm trying to drag
BOTH sides of this war to a moderate position.  Cladistics and eclecticism
are NOT mutually incompatible if the two opposing camps really wanted to
forge a common approach that incorporates the best each side has to offer.
And please don't argue it's like being partially pregnant.  I get so tired
of hearing that flimsy strawman argument.



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