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Re: Class-less dinosaurs
From: firstname.lastname@example.org (Phillip Bigelow)
> Putting dinosaurs into their own Class seems to be a less inflamatory issue
> than is moving birds out of Class Aves. One reason for this could be the
> rigidity of classical Linnaean systematics. One question that needs
> to be asked is whether the Linnaean system was constructed
> with the provision that it could be ammended? It appears, to me, at least,
> that Linnaean systematics is not easily ammendable, at least compared to
Partly this has to do with slightly differing purposes.
Cladism has as its primary - even sole - goal the elucidation of
evolutionary relationships. Cladism has made significant
contributions to this problem.
Classification, on the other hand, is as much concerned with
*information* *access*. It is in large part mainly a *filing*
*system*. (Note, this is why I place such a high importance on
the information theoretic issues brought up by Kent Carpenter
(who is a different person than Kenneth Carpenter)).
The way I see it, cladograms are the most appropriate way to
present the results of cladistic research. Classifications
need not follow the cladogram all that precisely, since they
have more need of stability. It is important, from an access
point of view, that the categories under which one looks things
up remain relatively stable.
> Further, it seems strange to have a systematic Class crammed inside another
> systematic Class. Not only is it counterintuitive, but it appears to be
> flat wrong.
But is *isn't* "inside". Just because it is descended from the
prior class doesn't make it "inside" it!
This is one of the main fallacies promoted by cladism. In
mathematics, classes can be defined by any combination of
assertions - including "negative" assertions. Thus retained
synplesiomorhies are as admissable in defining classes (in the
mathematical sense) as are synapomorphies. Since taxa, of any
rank, are primarily mathematical classes, and not strictly
biological entities, set membership need not nest in the same
way as derived features do.
The peace of God be with you.