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RE: Classification: A Definition



> > I personally would hate to see phylogeny made an obligatory part of
> > taxonomy. Firstly, because there are taxa out there that are
> > taxonomically distinguishable (due to possessing unique
> > characters), but may not be reliably placed in a phylogenetic
> > analysis at present (due to shortage of material or some such
> > reason).

> I don't see how that is a problem, though.  I have just such an animal
> in the works at the moment -- clearly new, very different from
> anything that already has a name, yet not resolvable with any
> confidence at all below the level Neosauropoda.  I'd call that
> Neosauropoda incertae sedis; would you instead prefer to give it a
> monogeneric family?  If so, to what end?

Not quite what I meant :-). I am fully sympathetic to the
no-monotypic-higher-taxa drive - I agree that they generally serve
little or no purpose, clutter up the literature and possibly even cause
harm by adding to the impression that taxa at the same "rank" are
somehow equivalent. However, if you had reasons to believe that your new
taxon was probably related to some other neosauropod of equally
uncertain position (for the sake of argument, let's say _Euhelopus_) but
were unable to rigorously test this phylogenetically, it might still be
useful to unite the two as "Euhelopodidae" as a means of highlighting
the likely connection. Ditto for if you thought it most likely a member
of Diplodocidae but couldn't prove it (maybe the biogeography, age, some
other factor that can't easily be entered into a phylogenetic matrix,
encourages this idea). Of course, this would be a provisional hypothesis
only and future researchers may bust this grouping wide open, but isn't
that how scientific investigation works?

One likely counter-argument that immediately comes to mind is that one
could just as easily use an informal name such as "euhelopodoids" or
comment in the paper on your reasons for thinking a relationship to
_Euhelopus_/Diplodocidae/whatever likely without expressing this as a
formal taxonomic assignation. My only reply to this argument is that
formal taxa seem to reach people's attention to a much higher degree
than informal groupings. Informal suggestions may be more easily
overlooked, or become buried among verbiage (especially if the paper is
not in one's native language). Imagine that the new phylogenetically
uncertain taxon is "probably Diplodocidae" and a later researcher
conducting a review of Diplodocidae runs some sort of database search
for all Diplodocidae at the beginning of their research to find what
taxa to include. If your taxon has actually been assigned to
Diplodocidae, the database search is much more likely to recover it than
otherwise.

One final point that I should probably make before this discussion moves
in an unintended direction - the points I've been making are not
intended as attacks on phylogenetic nomenclature _per se_. They are
arguments about making phylogeny a _sine qua non_ of nomenclature.

    Cheers,

        Christopher Taylor

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