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Re: The validity of cladograms (was Re: giant birds)



A couple of responses here:

Tracy Ford wrote:

> 
> That -certain select groups etc, is what I'm talking about. Capain Clade
> one, has a difference clade from Captain Clade two. Which one is right?
> Which clade is right. Those minor differences are major in the schme of
> things. They, for some of us, turn us off to clades.

You seem to be saying that because we can't (yet) achieve perfect
resolution in our phylogenetic summaries, something is seriously wrong. 
To paraphrase Darrel Frost (who may have been paraphrasing someone else,
I don't know), there's a difference between being able to say something
and not being able to say anything.  This is why I thought Paul Sereno's
method for summarizing different theropod hypotheses, in which he
constructed a strict consensus of different trees, was not appropriate -
his tree was very poorly resolved, but in fact there are less sensative
consensus methods available that would preserve the resolution found in
common with most published analyses.

And without the phylogenetic analyses we presently have, our capacity to
say anything about relationships would be much diminished.  We may not
be able to say everything, but we can certainly say more than nothing.  

Dinogeorge@aol.com wrote:

> I wonder how much of the stability arises from everybody using everybody 
> else's character matrices, rather than from a genuine phyletic signal. Might 
> be interesting to see what happens if one uses only skull characters in one 
> analysis versus only postcranial characters in another analysis.

Yes, it would.  Why not try it, George?  More to the point, why not
tease out all the differences between different analyses - literature-
versus specimen-based codings, taxon sampling, discrete versus ratio
characters, and so on?


chris


-- 
----------------------
Christopher A. Brochu
Department of Geology
Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, IL 60605

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