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Re: Greg Paul is right (again); or "Archie's not a birdy"
> You may well be correct on all these points. However,
> Pygostylia and Ornithothoraces will endure even if the
> contents of
> these clades change, or the phylogenetic brackets
> associated with
> individual apomorphies (or inferred behaviors based on
> apomorphies) change. Euornithes and Enantiornithes
> will remain sister
> taxa because they are mutually defined as such: _Passer
> but not _Sinornis santensis_ vs > _Sinornis santensis_
> but not _Passer
Provided a clean dichotomy. Our analyses by necessity treat "species" as
individuals with zero dimension in space and time. This assumption is usually
accurate enough (at least for nonmolecular datasets), but there is no guarantee
it is correct. And for paleontological datasets, it is usually not even
Besides, the neontological experience is that nodes as dichotomies may be more
fiction than fact - not always, but often (alternatively: that nodes as
dichotomies are arbitrary and evolutionary quite meaningless entities).
It is unlikely that this is a recent phenomenon.