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Re: where have all the etc.[Pharris]



Nick Pharris wrote:

<<[I]t is incumbent on you, who delight in making extraordinary claims, to
demonstrate that "your" characters outweigh "their" characters in a
phylogenetic analysis.  And there is no way to do that without including all of
"their" characters.>>

to which David Peters (davidrpeters@earthlink.net) replied:

<With dozens to choose from, some disagreeing with others, some not including
taxa that others do, which character list shall we start with? Name one and
I'll satisfy your challenge.>

  As with most phylogenetic analyses, either the most recent and work yourself
backwards, or the earliest and work forwards. Ideally, one should sample from
all given analyses fo a comprehensive look, and the history of theropod
dinosaur analyses are rife with this, as one of the fastest-expanding
phylogenetic regions in archosaurs to date (that and Brochu's studies on
various and sundry Crocodylomorpha, which is also getting very large). All one
has to do is look at the authorship of characters in a matrix to see that they
go back a long ways, some tending towards antiquity. Earlier authors usually
excluded characters for reasons and gave them. So too should anyone making
extraordinary claims.

<Extraordinary claims? Hardly. You should know that this study repeats the
results of earlier work whenever similar taxa are employed. The only time that
novel results appear is when novel taxa are introduced. Often the introduction
of novel taxa takes the form of using species or specimens rather than a priori
suprageneric taxa. That's why the larger, umbrella study has been necessary.>

  Let's face it, Dave: You are making extraordinary claims, as they are either
not followed by other researchers in the groups to which you contest the
relationship of, or are so unique they have not been found before. This
requires a MORE comprehensive look than excluding characters. If you cannot
find liusts of characters supporting Archosauria, Archosauriformes,
Archosauromorpha, Crocodyliformes, Crocodylomorpha, Crurotarsi,
Dinosauriformes, Dinosauromorpha, or Ornithodira, competing hypotheses, then
there is a whole list and dozens of websites including the data online willing
to share the data. Go to places like www.palaeos.com or here, and the data
flows out.

<Case in point: The only time (tell me if I'm wrong) that lizards and pteros
both appeared together in a cladogram (Benton 1985) they showed up as sister
taxa.>

  Pterosaurs have been regarded by a wealth of features to be held otherwise
than some few older groupings, and many, many strides have been made in the two
decades since Benton, 1985, both in computing software and phylogenetic theory.
But this data also included features supporting alternate groupings, and the
relationships were discussed and tested. Maybe not comprehensively, but Benton
did not exclude that data. And Benton (1999) also included this information and
found it lacking, as well. Sciences looks forward, not backward.

<Q: Why has this not been tested in later work? Why not by Benton?
 
A: A priori assumption and taxon exclusion.>

  This is just the reason why one should include ALL available data. Excuses
about taxon availability can be avoided by marking groups with "?" if
neccessary, or maintaining why one will not or cannot include them. Not
including substantial data on Archosauria or Crurotarsi does not, however, fall
under this grouping: This information is so extensive and available, it's on
the internet in more than one place.

  As for the 150-character "rule" ... literature literature literature. There
is so much data on the nature of inclusion of more information in a data system
and the use of feedback for improvement of this data that it fills the Library
of Congress. Try including 300 characters and show how this data is
superflouous or confusion, then we can discuss the use of reducing characters.

  Cheers,

Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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