Message 2001-06-0057: Re: [conflict between monophyletic taxonomy and rank-based classification]

Thu, 03 May 2001 22:30:05 -0700 (PDT)

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Date: Thu, 03 May 2001 22:30:05 -0700 (PDT)
From: "Jaime A. Headden" <>
Subject: Re: [conflict between monophyletic taxonomy and rank-based classification]

Ken Kinman ( wrote:

<In many cases, the well-defined clade is not only well-defined
but distinctive enough that it has often been raised to a higher
rank. One such an embedded clade is Aves which was so
distinctive that even primitive peoples paraphyletically removed
it from Reptilia. Not consciously of course, but this is how the
human brain normally classifies, at least when it hasn't been
conditioned to believe that paraphyly is something unnatural.>

  For some few thousand years, primitive peoples thought that
birds were "angelic" beings, supernatural, bridgers of worlds
between thought and death, life and darkness, etc. Ancient
concepts of birds were to demonstrate that although they exist,
no one knew _what_ they were. Not even Linnaeus "knew" what they
were, and placed them into a group (Aves) that was clearly a
member of the vertebrate "phylum". Further authors have bridged
the gap by attempting to see what other groups (read: other
classes) of vertebrate that birds pertained to. This has been
disputed up to today, so that while we see them as stemming from
within the reptile class, and the dinosaurs themselves (however
a person wants to rank them, that's been disputed, too), we are
finally catching up. Ancient concepts aside, I feel that they
were wrong for several millennia, and it was not for any choice
of a "they can't be members of Reptilia" but because of a poor
concept of the term "reptile." This, too, has clarifed over the
decades. Reptiles are hardly cold-blooded, sluggish animals.
Even traditional ones.

<We can have our cake and eat it too (at least in many cases),
but only if strict cladists come to realize that there is a
useful middle ground approach to classification, and that
semi-paraphyletic groups (or call them semi-holophyletic if that
makes them more palatable) often offer the best of both
traditional eclecticism and traditional cladism at the same

  How does one get to be semi-paraphyletic? You either are
monophyletic (stem from a natural ancestor) ... or are not (been
put there subjectively [for whatever reason, traditionally to
refer to typology and superficial similarity]). Semi-monophyly
or -holophyly or -paraphyly is like splitting concepts of
descent. Yes, I can be presented in one ancestor's phylogeny, or
another's, but I can be presented in both, not exclusively the

<I don't know what Jaime Headden meant when he mentionned a
"prescription for paraphyletic groups", but this is the kind of
compromise I have long prescribed (modified paraphyly that
results in cladistic nesting).>

  I personally feel the prescription offered makes official
recognition of paraphyletic taxa as a statement that they are
natural groups that can be recognized, and its up to the
reader's subjectivity to consider which group he'd rather
acknowledge. My recommendation is that paraphyletic taxa be
ignored, but that groups to reflect type can still be inferred
from lay terminology, as in "anapsid" compared to "Anapsida". If
Anapsida is considered paraphyletic, then the term anapsid can
still be applied in an historical context, but not in reflection
of its naturality by retaining the taxon name. Or, let me use
PhyloCode's recommendation: _Anapsida_ can be explicitly defined
in such a way that would clarify its life as a monophyletic
taxon ... but the term anapsid will always remain as a junkyard
novelty that one often wants go out and see, like one's
grandpa's Model-T.

  My prescription is therefore: Do not recognized paraphyletic
taxa, only groups in which typological information can be
conveyed. If there are those who want a paraphyletic Reptilia
because they don't want a descendant (which most recognize as
occuring) like Aves to be included, for whatever typological or
historical reason, they can explicitly make a phrase to refer to
a Reptilia lacking Aves, not a taxon name. Perhaps the PhyloCode
can reflect this in its articles?

Jaime A. Headden

  Where the Wind Comes Sweeping Down the Pampas!!!!

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