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Date: Tue, 14 Sep 2004 23:30:10 +0200
From: [unknown]
To: PML <phylocode@ouvaxa.cats.ohiou.edu>
Subject: The Pancompromise?
Most people could, I think, probably live with a recommendation that = looked 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= vention 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. = In addition, it's half past 11 pm over here, so chances are high that I'= ve 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 = of 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= ble that has, with varying degrees of explicitness, been applied to both = clades, 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= name of their panstems. It is also suggested to use this convention for ne= w 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= ludes the extant Arthropoda, Tardigrada and Onychophora as well as fossils = that could be outside the smallest clade formed by all three and has no sy= nonym 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= crown. Tetraconata has been used at least once to include the crown but excl= ude what was in that paper found to be its sistergroup, the extinct Euthycarcinoidea.) It would become necessary to put "panstem" into the glossary -- consi= dering how often this word has been used on this list, this is probably inev= itable 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= ting codes to convey information on ranks). ------------------------------------------ I suggest this to express the fact that I like the tradition that sta= rted with names like Lepidosauromorpha and Archosauromorpha (which, as usu= ally 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= ups 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>