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Date: Tue, 15 Jun 2004 21:27:20 -0700 (PDT)
From: "Jaime A. Headden" <qilongia@yahoo.com>
To: dinosaur@usc.edu
Cc: twilliams_alpha@hotmail.com, phylocode@ouvaxa.cats.ohiou.edu
Subject: RE: First International Phylogenetic Nomenclature Meeting
Tim Williams (twilliams_alpha@hotmail.com) wrote: <_Megalosaurus bucklandii_ might be a nomen dubium. Rauhut seems to think so. It's probably a bad idea using nomina dubia as specifiers, so I can see why _M. bucklandii_ might have been shoved aside.> Both *M. bucklandii* and *C. montanus* are admittedly dubious names, with limited application to diagnosing taxa. They are distinct largely historically. However, to use *Megalosaurus* as was done follows: Article 11, Recommendation 11A: "Definitions of converted clade names should be stated in a way that attempts to capture the spirit of historical use to the degree that it is consistent with the contemporary concept of monophyly. Consequently, they should not necessitate, though they may allow, the inclusion of subtaxa that were historically excluded from the taxon. To accomplish this goal, internal specifiers of converted clade names should be chosen from among the set of taxa that were considered to form part of a taxon under either the original or traditional ideas about the composition of that taxon, and they should not include members of subtaxa that were not historically considered part of the taxon." Example 1: "The name Dinosauria was coined by Owen for the taxa *Megalosaurus,* *Iguanodon,* and *Hylaeosaurus,* and traditionally the taxon designated by that name has included these and certain other non-volant reptiles. It has not traditionally included birds. Although birds are now considered part of the dinosaur clade, the name Dinosauria should not be defined using any bird species as internal specifiers. Such a definition would force birds to be dinosaurs, thus trivializing the question of whether birds are dinosaurs. Instead, internal specifiers should be chosen from among taxa that have traditionally been considered dinosaurs; e.g., *Megalosaurus bucklandi* von Meyer 1832, *Iguanodon bernissartensis* Boulenger in Beneden 1881, and *Hylaeosaurus armatus* Mantell 1833." One should note that while the actual holotype species of *Iguanodon* is *I. anglicus,* the NEOtype is *I. bernissartensis.* Thus, Owen's original inclusion is NOT "*Iguanodon bernissartensis* Boulenger in Beneden 1881," but rather, it is "*Iguanodon anglicum* [sic] Holl, 1829." In order to preserve consistency with the historical record, the original nomenclature is prefered. Jon Wagner (speaking for ya bud) is aware of this and I think considers it the lesser of two evils. <.... _Ceratops montanus_ is probably a nomen dubium.> Given that *Ceratops montanus* is THE nominative taxon for Ceratopsia, it could be unwise to use another internal specifier. Phylocode, Article 11.8: "In the interest of consistency with the preexisting codes, it would be desirable for a clade whose name is converted from a genus name under a preexisting code, or is derived from the stem of a genus name, to include the type of the genus name. Therefore, when a clade name is converted from a preexisting genus name or is a new or converted name derived from the stem of a genus name, the definition of the clade name must use the type species of that genus name at the time of establishment as an internal specifier." and Article 9, Recommendation 9B: "Establishment of names for poorly supported clades should be done with careful consideration of possible nomenclatural consequences if the phylogenetic hypothesis turns out to be incorrect. It may frequently be advisable to use only informal names for poorly supported clades." To use *Triceratops,* the next oldest available taxon that is considered valud, one could just name a new clade Triceratopsia, or define the clade as an apomorphy-based taxon, for find exception. On the other hand, some HAVE suggested *Ceratops* may be valid ... I think Dodson suggested *Avaceratops* and *Ceratops* may be synonyms or sister-taxa. I forget. Cheers, ===== Jaime A. Headden Little steps are often the hardest to take. We are too used to making leaps in the face of adversity, that a simple skip is so hard to do. We should all learn to walk soft, walk small, see the world around us rather than zoom by it. "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969) __________________________________ Do you Yahoo!? Yahoo! Mail is new and improved - Check it out! http://promotions.yahoo.com/new_mail