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Date: Mon, 13 Sep 2004 11:54:35 -0400
From: [unknown]
To: phylocode@ouvaxa.cats.ohiou.edu
Subject: Re: Panstems
Mickey Mortimerwrote- Pan-stems already disrupt continuity for many names, as most total cl= ades whose surrounding topologies are well known have been named already. >This is true in the sense that some non-Pan names have already been = =3D defined as referring to total clades; however, the names have a much = =3D longer history than this, and they have also been associated with = =3D non-total clades (even after their first phylogenetic definitions), s= o =3D there is no disruption of continuity in the sense of loss of the name= s. =3D Obviously, adopting a universal convention for a particular type of n= ame =3D will not be without some negative consequences. These consequences h= ave =3D to be weighed against the benefit of making it a lot more easy to = =3D recognize the names, especially for people who work on other taxa (su= ch as =3D plants) and are familar with names such as Aves and Mammalia, but not= with =3D Ornithosuchia (or 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 been one of the people w= ho =3D first defined several of them phylogenetically (de Queiroz and Gauthi= er, =3D 1992). Nevertheless, I think it would be a mistake to get too attach= ed to =3D these defintions, given that they have to official status under the = =3D PhyloCode (which will not be retroactive). More importantly, as I th= ink =3D was stated in some earlier version of the PhyloCode preface or the = =3D webpage, the period of time between the first proposal of phylogeneti= c =3D definitions and the offical implementation of the PhyloCode is suppos= ed to =3D be treated as a period for experimentation. If we decide that we cou= ld do =3D some things better, given a second chance, we should not let our earl= ier =3D decisions (mistakes?) constrain us.< In addition, basically every 'family' or 'order'-level clade with liv= ing representatives is understood to include some taxa basal to the crown version of that clade. So taxa directly basal to crown galliformes a= re placed in Galliformes too (e.g. Paraortygoides in Dyke and Van Tuinen= , 2004). Yet you would have us redefine Galliformes to be a crown clad= e, =3D and make Paraortygoides a non-galliform pangalliform. It's the same with Diacodexis and Artiodactyla, Basilosaurus and Cetacea, etc.. >Continuity is never 100% in terms of hypothesized composition. I wa= s =3D more concerned with the total loss of certain names--i.e., if ALL of = the =3D names are given standard affixes.< Have existing total clade names been associated with more alternate definitions than other kinds of clade names? I don't think so. The = most controversial clade names (Aves, Tetrapoda, Mammalia) are either crow= n or non-crown node-based clades. If you really want to introduce a stand= ardize=3D d affix, crown clades have the least names associated with them. But I= =3D agree with Jaime that recommending affixes for only one type of definition = is nonsensical. Perhaps a better recommendation would be to keep existi= ng names the same, but if you want to name a crown or total clade equiva= lent =3D to an existing clade, use the pan- or acro- affixes. This would cut dow= n on memorizing new clade names AND avoid disruptive renaming. >I wasn't suggesting that names associated with total clades have bee= n =3D associated with more alternative definitions than those associated wi= th =3D other types of clades. More importantly, if neonotologists (i.e., th= e =3D majortiy of biologists) acutally used the proposed crown clade names = =3D (e.g., Neotetrapoda, Neornithes) when talking about traits that can o= nly =3D be assessed in living organisms (and not in fossils), then I agree th= at it =3D would be logical to use the widely known names (e.g., Mammalia) for = =3D apomorphy-based clades and coin new names based on standard affixes f= or =3D the crowns (e.g., AcroMammalia). Unfortunately, they don't.< Kevin de Queiroz Division of Amphibians & Reptiles Smithsonian Institution P.O. Box 37012 NHB, Room W203, MRC 162 Washington, D.C. 20013-7012 Voice: 202.633.0727 FAX: 202.357.3043 E-mail: dequeirk@si.edu