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Re: Centrosaurines

> I have always agreed that taxa SHOULD be monophyletic--unless the
> accumulation of evolutionary novelties in a subclade makes retention of that
> subclade within the more inclusive clade "ridiculous"--like extant birds in
> Dinosauria. Since my starting point before forming taxa is always the
> cladogram, all phylogenetic information is preserved in my taxonomy. Derived
> birds are treated as dinosaur descendants, not as dinosaurs; the phyletic
> relationship is exactly homeomorphic to a set-inculsive relationship. Aside
> from the trivial novelty of thinking of birds "as" dinosaurs, retaining a
> monophyletic Dinosauria tells us nothing about birds that a paraphyletic
> Dinosauria ancestral to Aves doesn't.

    On misconception I had when I responded to G.O.s(??) posting on 
transitional forms in a cladogram was that a cladogram is a 
"family tree".  It is not, merely a chart of characteristics.  It might 
well be a useful tool, or even the most important tool in constructing a 
phylogenetic tree, but I think G.O. has the right idea in that you have 
to consider other factors as well.   
LN Jeff