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Date: Tue, 06 Feb 2001 19:34:59 +0100
From: David Marjanovic <David.Marjanovic@gmx.at>
To: PhyloCode mailing list <PhyloCode@ouvaxa.cats.ohiou.edu>
Subject: Re: apomorphy-based names
> When one examines the way in which certain names are used, it becomes very clear that some people > have an apomorphy-based concept of the clade to which they are referring. For example, some > authors clearly wish to name the clade stemming from the first vetebrate species to evolve feathers > rather than either the clade of Passer domesticus and everything sharing a more recent common > ancestor with it than with Deinonychus antirrhopus, or the clade stemming from the most recent > common ancestor of Passer domesticus and Archaeopteryx lighographica. Well, if we define Aves apomorphically on feathers, lots of other theropods, at least all coelurosaurs, are birds... > "I hope that one day the vertebrate paeontological types, and whoever else is inclined towards > apomorphy-based definitions, can be convinced to make-do with stem-based and node-based > definitions." > > It probably isn't a coincidence that paleontologists may want to name apomorphy-based clade > concepts more often than do neontologists. After all, paleontologists often (though not always) have > to make finer distinctions than neontologists. Thus, for neontologists, all of the clades that I described > above (i.e., clade from first featered vert; clade P. domesticus <-- D. antirrhopus; and clade A. > lithographica + P. domesticus) all have precisely the same composition (i.e., considering only extant > organisms). But for paleontologists, the composition of these taxa differs, and thus additional names, > which neontologists can do without, are often useful for them. See above.