Message 2004-10-0086: Re: Panstems

Tue, 14 Sep 2004 14:47:14 -0700 (PDT)

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Date: Tue, 14 Sep 2004 14:47:14 -0700 (PDT)
From: [unknown]
To: Christopher Taylor <>
Cc: Mailing List - Dinosaur <>, Mailing List - PhyloCode <>
Subject: Re: Panstems

--- Christopher Taylor <> wrote:

> On 14/9/04 8:19 am, "T. Michael Keesey" <> wro=
> >
>     One point which I've noticed in the exemplar definitions, which=
 isn't a
> problem with Mike's proposed notation, but a problem arising from o=
ne of the
> definitions -'Panaves'. My question is - how are we to properly def=
ine crown
> clades? Simply defining them as node clades doesn't seem sufficient=
, as we
> should allow for the possibility that some of the living members ma=
> eventually be moved phylogenetically outside the proposed node.
>     Mike defines Panaves as the panstem clade of the node Struthio =
+ Tetrao
> + Vultur.

Actually, de Queiroz and Gauthier did (in the Ostrom Symposium volume=

It should also be pointed out that _Tetrao_ is not a specifier. _Tetr=
ao major_
is the specifier, and it has been given its own genus since its origi=
publication: _Tinamus_. I was merely citing the original form of the =

> Under the current popular phylogenies, this wouldn't really be a
> problem - whichever the most basal branch of Aves is, most research=
ers would
> currently hold it to include one of these three. But among other ta=
xa that
> have been suggested in the past to be the most divergent living bir=
ds are
> Mesitornithidae, _Opisthocomus_ and _Todus_ (!). Conceivably, we co=
uld get a
> situation where these are not Aves. By some older molecular phyloge=
> Passeriformes would not even be Aves by the definition given. What =
to do?

You could use a stem-modified crown, e.g. "the first ancestor of all =
extant organisms sharing more recent ancestry with _Vultur gryphus_ t=
han with
_Archaeopteryx lithographica_, plus all of that ancestors' descendant=
s". That,
or increase the number of internal specifiers.

There has been some discussion about the general topic of crown and p=
clades on the PhyloCode Mailing List lately. Once again I urge everyo=
interested in this topic to join. The instructions, once again, from

"If you would like to join an internet discussion group focusing on
phylogenetic nomenclature, send a message to The =
should read: 'subscribe PhyloCode' (without the quotation marks). Do =
include anything else in the message. In a short time, you should rec=
eive an
automatic reply explaining how to send messages to the discussion gro=

=3D=3D=3D=3D=3D> T. Michael Keesey <>
=3D=3D=3D=3D=3D> The Dinosauricon <>
=3D=3D=3D=3D=3D> Instant Messenger <Ric Blayze>

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