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Date: Mon, 13 Sep 2004 18:49:05 +0200
From: [unknown]
To: phylocode@ouvaxa.cats.ohiou.edu
Subject: Re: Panstems
Dear phylocoders, Kevin wrote: > >This is true in the sense that some non-Pan=3D20 >names have already been defined as referring to=3D20 >total clades; however, the names have a much=3D20 >longer history than this, and they have also=3D20 >been associated with non-total clades (even=3D20 >after their first phylogenetic definitions), so=3D20 >there is no disruption of continuity in the=3D20 >sense of loss of the names. =09I don't entirely agree here. There is=3D20 disruption of usage if the most common meaning of=3D20 the name was the stem-based clade or a comparable=3D20 taxon under rank-based codes, or if that name=3D20 used most often for that stem-based clade would=3D20 be lost in favour of a Pan-based name. This is=3D20 certainly the case of Synapsida (=3D3DPanMammalia),=3D20 to cite my favourite example. >Obviously, adopting a universal convention for a=3D20 >particular type of name will not be without some=3D20 >negative consequences. These consequences have=3D20 >to be weighed against the benefit of making it a=3D20 >lot more easy to recognize the names, especially=3D20 >for people who work on other taxa (such as=3D20 >plants) and are familar with names such as Aves=3D20 >and Mammalia, but not with Ornithosuchia (or=3D20 >Avemetatarsalia) and Synapsida.< > >Here are some total clade names that come to mind- >Amphibia =3D3D Panlissamphibia. >Salientia =3D3D Pananura. >Urodela =3D3D Pancaudata. >Reptiliomorpha =3D3D Panamniota. >Synapsida =3D3D Panmammalia. >Metatheria =3D3D Panmarsupalia. >Eutheria =3D3D Panplacentalia. >Sauropsida =3D3D Panreptilia. >Anapsida =3D3D Pantestudines. >Romeriida =3D3D Pansauria. >Lepidosauromorpha =3D3D Panlepidosauria. >Archosauromorpha =3D3D Panarchosauria. >Avemetatarsalia =3D3D Panaves. > >Many of these names are very commonly used. Changing them all would= be >quite disruptive. > > >Obviously, I'm aware of these names, having=3D20 >been one of the people who first defined several=3D20 >of them phylogenetically (de Queiroz and=3D20 >Gauthier, 1992). Nevertheless, I think it would=3D20 >be a mistake to get too attached to these=3D20 >defintions, given that they have to official=3D20 >status under the PhyloCode (which will not be=3D20 >retroactive). =09Here, I believe that Kevin is=3D20 disregarding a point that some of us tried to=3D20 make at the meeting and that is related to=3D20 Mickey's comment. Namely, systematists want to=3D20 keep these names for stem-based clades because=3D20 this is more or less the way that they have been=3D20 conceptualized (or at least delimited) by=3D20 generations of systematists. For about a=3D20 century, Synapsida has referred to the stem of=3D20 Mammalia, and in the last 20 years or so, it has=3D20 come to include mammals too, a necessary change=3D20 to make it monophyletic. It is because of the=3D20 long history of this name that many of us want to=3D20 keep it, not because Kevin and Jacques defined it=3D20 twelve years ago (although I agreed with the=3D20 definition that they provided at the time and=3D20 have used the name in that sense consistently).=3D20 Parenthetically, other taxa have a lateral=3D20 fenestra but were not included in Synapsida (at=3D20 least in the last 50 years), such as some=3D20 parareptiles. Indeed, the fenestra is so common=3D20 in early amniotes that Reisz raised the=3D20 possibility that it might be an apomorphy of=3D20 amniotes lost in the "anapsids", so redefining=3D20 Synapsida on the basis of the fenestra would be=3D20 a really bad idea. Similarly, when I proposed=3D20 (with Reisz) phylogenetic definitions of=3D20 Parareptilia (=3D3DPanTestudines) and Eureptilia=3D20 (=3D3DPanSauria), I used Everett Olson's terminology=3D20 (proposed in the 1940s), that had been used by=3D20 several other paleontologists (even in Russia).=3D20 If I want to keep these names, it is not only=3D20 (not even mostly) because we have used these=3D20 names in the last 10 years in PN but rather,=3D20 because these definitions reflect the use of=3D20 these names in the literature (rank-based and PN). =09One of the most common critique of the=3D20 PhyloCode is that it will generate many new names=3D20 and disrupt continuity with the literature; that=3D20 is certainly not true of the PhyloCode as it now=3D20 stands, but it COULD be true if the use of the=3D20 Pan- prefix for total clades is made mandatory=3D20 for most such clades. Let's not give critiques=3D20 of the PhyloCode such an obvious problem to point=3D20 out. =09Sincerely, =09Michel --=20 Michel Laurin =3D46RE 2696, CNRS Universit=3DE9 Paris 7 - Denis Diderot 2, place Jussieu case 7077 75005 Paris =3D46RANCE tel. (33 1) 44 27 36 92 http://tolweb.org/tree/laurin/Laurin_Home_page.html Secretary of the International Society for Phylogenetic Nomenclature