DEVELOPING A PROTOCOL FOR THE CONVERSION OF RANK-BASED TAXON NAMES TO PHYLOGENETICALLY DEFINED CLADE NAMES, AS EXEMPLIFIED BY TURTLES

Journal of Paleontology, Sep 2004 by Joyce, Walter G, Parham, James F, Gauthier, Jacques Armand

Among the plethora of namable clades, this contribution focuses on naming the crowns and panstems of the well-known clades of turtles (Gauthier and de Queiroz, 2001). Crown clades are clades delimited by living representatives (e.g., the clade that originates from the last common ancestor of all living turtles). In contrast, panstem clades are clades that include crowns, but are also specified by the next living representatives from outside of those crowns (e.g., the clade that contains living turtles plus all organisms more closely related to living turtles than to any other living organism). This emphasis on naming clades delimited by extant specifiers does not imply that fossils are somehow less deserving of our attention or that this article is not relevant to paleontologists. Quite to the contrary, we predict that this contribution will be of particular interest to paleontologists. This is because crown and panstem clades are precisely those clades about which neontologists and paleontologists so often want to communicate. At a time when morphological data from "stem groups" and age estimates of crown clades are arguably the most important contributions that paleontologists make to systematic biology, it is consequently of singular importance for all paleontologists to appreciate the differences among stem-, node-, and apomorphy-based clade names in order to be able to communicate precisely their findings to their neontological colleagues using a nomenclatural system shared by both communities.

Abbreviations and notes.-Abbreviations used include: NCN for New Clade Name; CCN for Converted Clade Name; and Orig.' to denote original taxonomic reference. We provide full citations for the names of specifier species (s. PhyloCode, 2003, Article 11.1) used in the main text. For the citations of all other species names listed in the Appendices, please refer to King and Burke (1989) or Iverson (1992). Throughout the text, double quotes are used when citing literally. In contrast, single quotes are used to highlight a particular word, not its meaning.

METHODS

A comprehensive literature search was undertaken to reconstruct the history of the systematics, taxonomy, and nomenclature of fossil and Recent turtles, with an emphasis on understanding the nomenclatural history of the major crown clades (i.e., clades delimited by extant species). A number of previously published reviews proved particularly useful starting points, such as Boulenger (1889), Siebenrock (1909), Hunt (1958), Kuhn (1961, 1967), Gaffney (1984), Bour and Dubois (1985, 1986), and King and Burke (1989). Special emphasis was placed on reading all primary literature, and not relying on secondary references, to avoid propagating incorrectly cited ideas about turtle taxa as governed by the ICZN (1999) and their associated circumscriptions and names. All books and articles used herein were searched for turtle-related ICZN-taxon names as well as their differentiating characters (= differentia) and proposed composition (= usages) with the aim of creating synonymy lists, that is, lists of names that apply to (arguably) comparable circumscriptions (non s. ICZN, 1999 and PhyloCode, 2003; see below). Following the current rules of the ICZN (1999), we consider only formal Latin names and ignore all literature using vernacular English, French, German, or Italian terms, such as 'Ch�loniens' (Brongniart, 180Oa, 180Ob) or 'Testuggini' (Bonaparte, 1836b). This literature review is the basis against which we test ideas regarding current and past nomenclatural practices. It also serves as the foundation for the transitional protocols that we develop and the phylogenetic nomenclature of turtles that we propose.