[Taxacom] middle ground approaches (in both paraphyly and the end-Cretaceous extinctions)

Kenneth Kinman kinman at hotmail.com
Tue Aug 14 08:07:57 CDT 2018


John asked: "Wonder what a half paraphyletic/monophyletic group looks like?"

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       I have been presenting such groups in classifications on Taxacom for years (which I call "semi-paraphyletic" or if you prefer "semi-holophyletic").  This middle ground approach is to insert a semi-paraphyletic marker {{in double brackets}} to show the cladistic placement of a taxon (exgroup) that has been "removed".  It's not really completely removed since the marker shows its cladistic placement in the mother taxon.  Such a cross-referencing system in a classification can make classifications much more stable and therefore more useful.

     The alphanumeric coding to the left of the taxon names can be ignored if you are not interested in their cladistic relationships.  I also put a % sign after a singly paraphyletic taxon (a double %% for the rare doubly paraphyletic taxon like Reptilia).  All this is illustrated in part of the Reptilia classification which I posted here back in 2004:


     _1_ Subclass Lepidosauria% (basal diapsids)
          1  Araeosceliformes
          2  Plesion Coelurosauravus
          3  Plesion Apsisaurus
          4  Younginiformes
          5  Eolacertiliformes
          B  Sphenodontiformes
          C  Squamatiformes
          6  Ichthyosauriformes
          B  Sauropterygiformes
          ?  Thalattosauriformes
          7  Choristoderiformes
          8  Trilophosauriformes
          B  Rhynchosauriformes
          9  Protorosauriformes
         10  Proterosuchiformes%
         _a_  {{Archosauria}}

    _1_ Subclass Archosauria% (ruling reptiles)
          1  Suchiformes% (basal crurotarsans)
         _a_  Crocodyliformes
          2  Plesion Scleromochlus
          B  Pterosauriformes
          3  Dinosauriformes%
         _a_  {{Aves}}

_a_ CLASS AVES




________________________________
From: John Grehan <calabar.john at gmail.com>
Sent: Monday, August 13, 2018 8:23 PM
To: Kenneth Kinman
Cc: Taxacom
Subject: Re: [Taxacom] middle ground approaches (in both paraphyly and the end-Cretaceous extinctions)

Ken's appeal for middle ground may be laudable, but its not really pertinent to science. The idea of 'middle ground' is a political concept, a sort of juggling of different opinions where each gives up some of their position to accommodate others. This is not science in the sense that science is about trying to identify what is going on in the universe and so far as we may understand the universe, there is no middle ground. Either something is or it is not and selecting an opinion between conflicting views of what is or is not has nothing to do what what really is or is not.

Deciding to utilize groupings that leave out some of their members is certainly a choice that anyone is free to make. And if there is a majority opinion to recognize some as such then fine, but its just a political decision (all decisions that require a vote are political, just like whether Pluto is a planet or not).

Wonder what a half paraphyletic/monophyletic group looks like?

John Grehan

On Mon, Aug 13, 2018 at 8:29 PM, Kenneth Kinman <kinman at hotmail.com<mailto:kinman at hotmail.com>> wrote:
Hi All,

      As one who usually looks for a middle ground, I think this nasty feud was senseless.  The volcanic eruptions were massive and certainly would have had a severe impact on biodiversity.  But it would have been the asteroid impact that finished off the dinosaurs that remained (as well as other taxa).  If it weren't for this double whammy (massive volcanism followed by an enormous impact), some dinosaurs might have gotten through it.  But the one-two punch was just too much.  Such a middle ground view makes sense, and it would have avoided a senseless and nasty feud.

                   --------------Ken

P.S.  The current feud over formal paraphyletic taxa is also senseless.  Instead of two extremes (the zero paraphyly of strict cladism vs. the old excessive use of paraphyly), a middle ground recognizing the most useful and least controversial paraphyletic taxa would be a perfect middle ground approach.





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