Message 2001-02-0018: Re: apomorphy-based names

Tue, 06 Feb 2001 19:34:59 +0100

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Date: Tue, 06 Feb 2001 19:34:59 +0100
From: David Marjanovic <>
To: PhyloCode mailing list <>
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.


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