First International Phylogenetic Nomenclature Meeting, Paris 2004

Kipling Will kiplingw at NATURE.BERKELEY.EDU
Thu Jul 3 13:13:07 CDT 2003

T. Michael Keesey wrote:
> This still doesn't solve the problem of where to place ancestral species.

I guess I will worry about that when the problem of how to objectively
recognize an ancestral species is solved.

> You could possibly get around the problem of running out of ranks by leaving
> many taxa unnamed, e.g., for Vertebrata, make Classes out of Pteraspidomorphi,
> Chondrichthyes (sense stricto), Actinopterygii, Dipnoi, Coelacanthomorpha,
> Lissamphibia, Mammalia, Testudines, Lepidosauria, Crocodylia, and Aves. But
> then you leave a lot of fossil taxa with no Class (_Ichthyostega_,
> _Dimetrodon_, etc.). Furthermore, you have sacrificed such taxa as
> Gnathostomata, Osteichthyes, Sarcopterygii, Tetrapoda, Amniota, Sauropsida,
> Sauria, and Archosauria. I don't see that keeping the arbitrary ranks is worth
> this sacrifice.
> I agree that all formal taxa should be clades (or species ... I think), but I
> don't see how this is workable with the Linnaean hierarchy of absolute ranks.
> Nor do I see the real value of absolute ranks. (Look above -- what is gained by
> saying that Dipnoi [lungfishes] and Mammalia are Classes?)

In any classification where they are ranked as Classes, it is
immediately, and even without a cladogram, evident that they are
exclusive groups and are not contained in *any* other Class in that
classification. Without an absolute rank, Dipnoi is a group that may
contain Mammalia or the other way around, or they may be two separate
groups. Information-free nomenclature?

we can do better.

kip will

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