Plesions and plesiomorphons (not the same)

Ken Kinman kinman2 at YAHOO.COM
Thu Mar 17 21:14:14 CST 2005

     I thought my example made this clear, but apparently not.  Each tooth of the Hennigian comb (preceding the crown clade) is a separate plesion.  Only if you lump two or more plesions together into a plesiomorphon do you get a paraphyletic group.  I wish I had my copy of Wiley here, but I think you probably misinterpreted what he said as well.  Plesions are individual members of the pectinate series (NOT the whole series as a single entity).

     The reason for plesions was mainly to keep strict cladism from destroying the Linnaean ranking system.  McKenna's mammal classifications introduced all kinds of weird new ranks, like Mirorder, Magnorder, and a bunch or others I can't remember offhand.

     Another remedy was Wiley's convention of "phyletic sequencing" for Hennigian combs (of both living AND fossil taxa).  According to this convention, each unannotated clade was a sister group to the all the rest of the taxa which followed.  As I stated on page 53 of my 1994 book, I do not "feel that it is best to use a negative (un-annotated) convention for indicating a positive knowledge of sequencing.  Therefore the Kinman Code uses a positive code for sequencing [namely, numbers and letters] and uses the "negative" lack of code for a negative occurrence, namely lack of knowledge (sedis mutabilis)."  Perhaps if Wiley's phyletic sequencing had been annotated, rather than un-annotated, it might have actually caught on. Unfortunately, this failure made it almost inevitable that some strict cladists would eventually abandon ranks altogether.  The PhyloCode is in some ways just the product of a whole series of mistakes and missed opportunities over the years.  And that doesn't even include the very early mistake of Hennig's "no paraphyly" rule that led to all these problems in the first place.
      ------Ken Kinman
P.S.  One of the purposes of the Kinman System IS to produce classifications that can be converted back into cladograms.   In fact, you can draw a cladogram in the margins of my classifications if that makes it easier to visualize.

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