Re: Postorbital processes (& weighting??)

["T. Mike Keesey" <tmk@dinosauricon.com>]

On Mon, 17 Dec 2001, Ken Kinman wrote:

>      Nope.  Feduccia, Martin, and colleagues recognize a holophyletic
> Sauriurae (which goes all the way back to Archaeopteryx).
>      According to their phylogeny, Aves would be a heterodefinitional
> synonym of Ornithothoraces (the latter would then be more inclusive than
> Pygostylia, not less).  So whether Ornithothoraces includes
> confuciusornithids (or not) depends entirely on whose phylogeny you are
> looking at.

But they include _Confuciusornis_ (one of the specifiers for
_Pygostylia_, IIRC) in Saururae, so _Pygostylia_ also becomes a synonym of
_Aves_.

>      This is another good example of why I don't like anchored taxa.

But if they were right (...), then we'd be getting rid of
_Ornithothoraces_ and _Pygostylia_ anyway. The definitions simply clarify
with precision which conditions we abandon clades under.

> Traditional taxa based on good characters don't have near that much
> potential instability (of content) built into them.

If the characters are "good", why should it matter whether it's a clade or
a traditional taxon? There are certainly examples of unstable traditional
taxa.

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