Re: BCF (was New Article in Experimental Zoology)

[Stephan Pickering <stefanpickering2002@yahoo.com>]

--- John Conway <john_conway@mac.com> wrote:
> 
> On Monday, August 26, 2002, at 06:12  PM, T. Michael
> Keesey wrote:
> 
> > Since the crown clades match the original content
> of such clades as 
> > _Aves_,
> > _Mammalia_, _Crocodylia_, etc., and since their
> traditional usages 
> > match the
> > crown clades more closely than they do the
> stem-based clades, it makes 
> > much
> > much more sense to apply them to the crown clades
> than the stem-based 
> > clades.
> > They were originally named for extant forms -- why
> should it not 
> > remain so?
> 
> But Gauthier's crown clade Aves excludes so many
> animals that most 
> people would call birds. _Archaeopteryx_ + _ Vultur
> gryphus_ is not a 
> crown clade as I understand it - but makes much more
> sense (the common 
> sort anyhow).
> 
> Many people have big problems with any definition of
> Aves that excludes 
> _Archaeopteryx_.
> 
> 
> John Conway, Palaeoartist
> 
> "All art is quite useless." - Oscar Wilde
> 
> Protosite: http://homepage.mac.com/john_conway/
> Systematic ramblings:
> http://homepage.mac.com/john_conway/phylogenetic/
> 
I'm afraid that all of this circumlocution is
unnecessary, as the bickering does not meet
evidentiary standards of scientific discussion. Mr
Conway concludes: "Many people have big problems with
any definition of Aves that excludes 'Archaeopteryx'".
Many people...who have not read, carefully, Jacques
Gauthier's/Kevin de Queiroz's 2001 phylogenetic
systematics. As they, and other scholars have noted,
there are at least four morphotypes of pre-K/T
feathers known, and, Gauthier/de Queriroz write, "now
feathers are no longer diagnostic of the clade
stemming from the Archaeopteryx node". There are
transformational series: hollow filaments, "natal"
down, pennaceous feathers, remiges and retrices (cf.
Gauthier/de Queiroz 2001:25). There were, simply put,
nonavian theropods with feathers who could, likely,
have flown/glided/become airborn. Gauthier/de Queiroz
make the cogent observation (2001:33): In our view, at
least five clades formerly designated as "Aves"
desedrve to be named in one way or another: (1) the
clade of bird-line archosaurs; (2) the clade of
feathered dinosaurs; (3)the clade of flying dinosaurs;
(4) the clade stemming from the Archaeopteryx node;
and (5) the clade of crown dinosaurs.
    I do not discern the "problem" Mr Conway alludes
to. "Aves" does not equal the Archaeopteryx node. In
other words, if one is to use a name for a clade, all
should use the same name for the same clade to
eradicate ambiguity. Archaeopteryx is a node within
Avialae but not Aves.
    If this not acceptable to Mr Conway, I await his
detailed analyses.

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