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Re: The iguanodont paper



On Dec 8, 2007 7:01 PM, Tim Williams <twilliams_alpha@hotmail.com> wrote:
>
> Mike Keesey wrote:
>
> > Actually, the apomorphy is "wings used for powered flight" -- so it's both.
>
> It's a tough gig trying to apply that particular definition to the fossil 
> record!

Agreed, but I think the basic idea behind the definition (Gauthier and
de Queiroz's) goes like this. Many people use the term "Aves" to refer
to the clade of flying dinosaurs. They come up with different
definitions and usages for it (Sereno's, Chiappe's, Marjanovic's,
etc.), but basically that is the clade they are trying to delimit.
That name, "Aves", is better used for the crown group, to limit
unjustified inferences. But since many people want to talk about the
clade of flying dinosaurs (whatever it includes), it seems a good idea
to name it. Then we can discuss, e.g., whether or not _Archaeopteryx_
and _Microraptor_ are avialans.

In summary, yes, we don't know exactly what belongs, but it's still an
interesting clade.

> I just re-read the Gauthier and de Queiroz paper that came up with 
> Aviremigia, Avipinna, etc.  I don't these these particular apomorohy-based 
> clades were actually formally erected and defined, just proposed as 
> prospective clades.

True, but that's also true of every clade definition -- there is no
such thing as a formal clade definition at present. It's the Wild West
until Sheriff PhyloCode (or someone) gets around to setting up office.

> As for Aviremigia, the (proposed) definition refers to the presence of 
> remiges and rectrices on the forelimbs and tail.

Ah, well, I was close.

-- 
T. Michael Keesey
Director of Technology
Exopolis, Inc.
2894 Rowena Avenue Ste. B
Los Angeles, California 90039
http://exopolis.com/
--
http://3lbmonkeybrain.blogspot.com/