Message 2004-10-0033: Fwd: Re: REPOST: Crowns, Panstems, and their Correspondence to each other

Mon, 13 Sep 2004 08:29:03 -0400

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Date: Mon, 13 Sep 2004 08:29:03 -0400
From: [unknown]
To: phylocode@ouvaxa.cats.ohiou.edu
Subject: Fwd: Re: REPOST: Crowns, Panstems, and their Correspondence to each other

>
>--- Kevin de Queiroz <Dequeiroz.Kevin@NMNH.SI.EDU> wrote:
>
>  > The approach we have taken is not to have a rule specifying the =
meaning of
>  > "extant" but to have a rule stating that a specified meaning (th=
e same one
>  > that TMK suggested) is to be adopted if the original author did =
not specify
>>  the meaning.  This gives the authors of definitions more freedom =
but also
>>  prevents ambiguity.  Here is the rule:
>>  9.5. If the author of a crown clade definition (Note 9.4.1) did n=
ot specify
>>  the meaning of "extant" or "crown clade" or an analogous term use=
d in the
>>  definition (e.g., "living", "Recent"), then subsequent authors ar=
e to
>>  interpret that definition as referring to organisms or species th=
at were
>>  extant on its publication date (Art. 5).
>


T. Michael Keesey wrote:

>Great idea!
>But for stability, mightn't it be good to specify "extant AND=20
>ALREADY PUBLISHED
>on its publication date"?
>

I don't think this addition would be a good idea.  If a species were=
=20
discovered a few years after an apomorphy-modified node-based=20
definition was published, and the species possessed the apomorphy=
=20
used in the definition but its other features suggested that it is=
=20
the most basal member of the crown clade, wouldn't we want it to be=
=20
included in the clade?  It was certainly extant a few years earlier;=
=20
it just hadn't been discovered yet.

Phil


--=20
Philip D. Cantino
Professor and Associate Chair
Department of Environmental and Plant Biology
Ohio University
Athens, OH 45701-2979
U.S.A.

Phone: (740) 593-1128; 593-1126
Fax: (740) 593-1130
e-mail: cantino@ohio.edu

  

Feedback to <mike@indexdata.com> is welcome!