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Re: BIRD STUFF AND CLADISTICS




<<This argument comes dangerously close to being circular. Cladistic 
analysis has uncovered a different relationship from that found by the 
traditional methodology, but this doesn't mean it is any more (or less) 
correct.>>

Agreed, but THREE different and INDEPENDENT analyses came to near 
IDENTICAL conclusions on the matter of _Presbyornis_.  Other analyses 
have come to the Anhimidae->Anseranatidae->Anatidae (Anseranatidae and 
Anatidae are placed together in Anseres) sequence. Now, this doesn't 
mean that you can't come to this conclusion through cladistic 
principles, it just shows that the approach that came up with the now 
unlikely hypothesis is of doubt.  I can, by your arguments, say that 
your BCF hypothesis (which is based on very similiar tenuous methods as 
the faulted Olson and Feduccia hypothesis) is any more or less true than 
BAMM.  I think, though, that the cladistic method yields more reliable 
solutions to phylogenetic problems since, as mentioned in my first 
email, the intuitive method bases huge reliance on few characters among 
other things.  (Take _Longisquama_ for example; is it good phylogenetics 
to say that it is near theropods because it has a furcula but other 
diagnostic theropod features are missing or incomplete?)

<<It is just different, and it certainly sheds no light on the 
reliability of cladistics just because it is different. Cladistic 
analysis may have found the true phylogeny >in this case<, but we have 
no way of knowing this, and it just as likely (or perhaps even more 
likely) that cladistic analysis didn't find the true phylogeny after 
all.>>

This phylogeny is highly corroborated by THREE analyses completely 
INDEPENDENTLY using similiar characters.  No doubt that the details will 
be interpreted differently or there will be slight variations, but this 
hypothesis is very strongly supported.  This hypothesis is much more 
strongly supported than the vague Olson and Feduccia hypothesis which 
depends only on a few characters of extremely questionable homology.  
Indeed, _Presbyornis_ appears to fill in an important gap in anseriform 
evolution, and this is based not only on morphological evidence, but 
ecomorphological evidence (summarized in Livezey, 1997).  I suggest that 
you get the paper and read it thoroughly George.

"Contrary to the dire predictions by Feduccia (1994, 1995, 1996), 
phylogenetic (cladistic) analysis of morphological and molecular data 
remains the only rigorous and philosophically grounded tool available 
for the reconstruction of higher-order relationships of birds.  
Phylogenetic techniques apply to fossils as well as modern taxa, and 
successful applications do not hinge on fossil 'mosaics' and can provide 
empirically deatiled, testable alternatives to intuitive evolutionary 
scenarios.  Phylogenetically placed, _Presbyornis_ provides further 
insights into the basal grade of Anseriformes but does not unite modern 
taxonomic orders.  For the Galliformes and Anseriforms, the modern 
Anhimidae and _Anseranas_ serve as outstanding examples of modern 
'links', critical taxa found not by exploration of the fossil record, 
but instead revealed through the study of modern endemics of the 
Southern Hemisphere" Livezey; 399.  

This is just one example of great quotes in the paper.  Though I agree 
that cladistics does not account for all major factors of evolution, I 
do think that it is an extremely valuable and sound tool for 
phylogenetic analysis that is not subject to large amounts of personal 
bias (this is not to say that there is no personal bias among cladists, 
just that there is less).  

Matt Troutman 
m_troutman@hotmail.com


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