[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: giant birds



I don't propose to answer all of George's points. I repeat, we either 
use a scientific method or we don't. I agree there are situations where 
cladistic analyses produce anomalous results. I've experienced these in 
my own work when comparing phylogenies based on molecular and 
morphological characters. A good example are the problems 
encountered in examining phyla-level relationships based on 18s rDNA 
(these problems are now known to be caused by unequal rates of 
evolution in the molecule across different lineages). However, by and 
large analyses performed on independent character sets come up with the 
same results. This should give us confidence that this is THE BEST 
METHOD AVAILABLE. The alternative is to resort to common sense or 
plausibility, as George puts it. Unfortunately, these are highly 
subjective criteria, hence the appeals to authority and ad hominem 
arguments seen lately. Subjectivity does not lend itself well to the 
testing of hypotheses. 

By the literature I meant peer-reviewed, international scientific 
journals. I have a copy of George's article in Omni magazine.

I still cannot see how BCF can be compatible with the published 
topology. If it was non-avian theropods would nest within aves, not the 
other way around. Saying "they're all birds" does not explain the 
problems BCF produces with character polarity at the base of the 
theropod tree. Analyses pretty consistently place avians as the 
sister-group to deinonychosaurs, not as the sister group to non-avian 
theropods. There are certainly list members much better equipped than 
me to address these issues, so let's hear from someone else. Is BCF 
compatible with the conventional phylogeny?

Kendall Clements

----------------------
Kendall Clements
k.clements@auckland.ac.nz