Message 2004-10-0084: The Pancompromise?

Tue, 14 Sep 2004 23:30:10 +0200

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Date: Tue, 14 Sep 2004 23:30:10 +0200
From: [unknown]
To: PML <>
Subject: The Pancompromise?

Most people could, I think, probably live with a recommendation that =
like my attempt below. I understand that the risk is high that both s=
ides of
the debate will not like it. I myself have to add that the *Pan-* con=
would make many people think that all clades that include extant memb=
ers and
don't start with *Pan-* would, at least by default, be crown-groups. =
addition, it's half past 11 pm over here, so chances are high that I'=
overlooked something important. :o)

For clarity, I should mention that I interpret Rec. 10A as to
de-facto-forbid *Panmammalia* and to de-facto-mandate the conversion =
either Synapsida or Theropsida to the name of that clade.

<climbing on soapbox>

In many areas of the tree of life, it has proven useful to name a
crown-group as well its panstem. Often one preexisting name is availa=
that has, with varying degrees of explicitness, been applied to both =
or only to the crown-group. It is suggested to define such preexistin=
g names
as crown-groups and to attach the suffix *Pan-* to them to derive the=
of their panstems. It is also suggested to use this convention for ne=
names. In both cases, however, care should be taken not to violate
Recommendation 10A, which could easily happen inadvertently.

This would probably necessitate another recommendation:

The prefix *Pan-* should not be used for clades that are not panstems=

Which, in turn, could make good use of an example (if the example is
correct, see below):

Recommendation [number of above] is an argument to prefer the convers=
ion of
Tetraconata over that of its synonym Pancrustacea, both of which are
preexisting node-based names that designate a clade that includes the
insects and crustaceans. However, when combined with Recommendation 1=
0A, it
is not an argument against the conversion of Panarthropoda, which inc=
the extant Arthropoda, Tardigrada and Onychophora as well as fossils =
could be outside the smallest clade formed by all three and has no sy=
apart from a rare usage of Arthropoda.

(Someone who knows this subject should control this, however -- I don=
't know
if Pancrustacea has been defined or at least explicitely used for the=
Tetraconata has been used at least once to include the crown but excl=
what was in that paper found to be its sistergroup, the extinct

It would become necessary to put "panstem" into the glossary -- consi=
how often this word has been used on this list, this is probably inev=
anyway, for example as:
"a stem-based clade that has a crown-group, or some member(s) thereof=
, as
its internal specifier(s) and the next living relative of the crown-g=
roup as
its external specifier(s)."

Perhaps it would be appealing to give the *Pan-* convention some cont=
ext, as
the following recommendation could do:

Authors are encouraged to give the names of sistergroups identical, i=
f any,
suffixes. This applies especially to the two stem-based clades of a
node-stem triplet. Care should, however, be taken to avoid implicatio=
ns of
rank if these are not desired (many suffixes are regulated by preexis=
codes to convey information on ranks).

I suggest this to express the fact that I like the tradition that sta=
with names like Lepidosauromorpha and Archosauromorpha (which, as usu=
defined, are the stem-based parts of a node-stem triplet). It also fi=
ts the
more philosophical idea (proposed by, for example, Ax) that sistergro=
should have equal rank (even if those "ranks" are nameless and theref=
ore as
invisible as in the PhyloCode; they are in Ax's works).

<descending from soapbox>


Feedback to <> is welcome!