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Re: giant birds



In a message dated 11/11/99 3:36:52 PM EST, k.clements@auckland.ac.nz writes:

<< It 
 would be a very simple matter to test BCF against other phylogenetic 
 hypotheses on the origins of bird flight. Take a theropod character 
 matrix of the sort used to produce Fig. 4 in Sereno's recent paper 
 (Science 284: 2137-2147), and run a simple maximum parsimony analysis 
 in PAUP. Open the tree (or trees in the event that there are multiple 
 shortest trees) in MacClade, and use branch swapping to produce the 
 topology corresponding to BCF. Compare the new tree length with the 
 original. There are more sophisticated statistical techniques for tree 
 comparison, but this would do for a start. I'd do it myself if I had a 
 character matrix! I will be very surprised if the BCF topology is 
 equally parsimonious, as George suggests. >>

This test will show that the phylogeny favored by the ornithologists, wherein 
birds and dinosaurs are not considered to be closely related, should be 
rejected. But it will not reject BCF, because BCF doesn't lead to a different 
phylogeny; it merely tells you what has happened in the phylogeny that most 
dinosaur paleontologists presently accept. The BCF tree topology is the same 
as the bird-dinosaur tree topology. There are parts of the currently accepted 
phylogeny that I think are incorrect and result from algorithmic artifacts of 
cladistic analysis, but these have nothing to do with BCF.