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Re: Cladistic taxonomy (was Dietary factors)



On Tue, 8 May 2001, philidor11 wrote:

> HP Williams had, I thought, considered that:
> In effect, if a genus is more closely related to modern birds than
> _Archaeopteryx_, then it is considered a bird *in the scientific sense*.

"Bird" is often (although not always) equated with "avian" -- the
definition of _Aves_ is "the most exclusive clade containing
_Archaeopteryx_ and modern birds", not "all taxa sharing more recent
ancestry with modern birds than with _Archaeopteryx_". (Just wanted to
clear that up for any readers. I don't think the latter clade is named,
although someone did try to pin _Ornithurae_ on it unsuccessfully, IIRC.)

> Archie is part of the _definition_ of  birds.

This is the second time I'm making this point today; Archie is NOT part of
the definition of "bird". "Bird" is a vernacular term that means whatever
the body of English speakers at large determine it to mean. Archie is part
of the definition of _Aves_, a formal taxon which is not necessarily the
same thing as "birds".

"Avian". It's only one letter longer than "bird", and so, so much more
precise.

> Bas VanFraassen sez: you don't need clear boundaries to have a legitimate
> distinction; all you need is a clear case of the one kinda thing and a clear
> case of the other kinda thing.

This works for vernacular terms like "bird". Not a great idea in formal
nomenclature, IMHO.

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