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Re: Greg Paul is right (again); or "Archie's not a birdy"



Sorry if repeating, but in my viewpoint, phylogenetic redefinitions
always generate confusion. "Aves", "Neornithes" and "Ornithurae" have
to be redefined this way to make them useful in phylogenetic
nomenclature. As "Avialae" was originally defined on the basis of
apomorphies (perhaps a remnant of typology, and at trouble in case of
convergence), this also applies to this group if we want to only use
stem- and node- based names. Some restriction (perhaps just
boycotting) should be in order against redefinitions, even if the
Phylocode is not enacted yet, similar to the way redefinition of
genera and species in the ICZN are prohibited. If the original Aves is
a typological concept, with even a large history before Linnaeus,
there does not seem to be a way to redefine it phylogenetically which
is without "buts". Attaching "Aves" to the crown let you say that all
birds have the non-fossil attributes currently considering as defining
them, but these same attributes, even the entire list, may not be
unique for them so they are useless as defining apomorphies. Of
course, attaching "Aves" to the stem (as Colin Patterson once
proposed) implies the soft-tissue features cannot be inferred for all
the members of the taxon, so neither does it help, or even less (I
don't remember Patterson's 1993 arguments for this strange idea). I
would prefer new terms, while we may keep speaking not formally about
an undefined series of feathery beasts as "birds"; this would not be
however scientific terminology. As today the stem- and node- based
definitions are preferred in phylogenetic parlance, perhaps
clumsy-looking new names as "Apexaves" or "Panapexaves" (of course,
something with better classical language grammar) can serve for the
crown- and stem- based definitions, whereas still bearing
reminiscences of the typological traditional names with which they
better overlap.

2011/8/2 Mike Keesey <keesey@gmail.com>:
> On Tue, Aug 2, 2011 at 6:03 AM, Mike Taylor <mike@indexdata.com> wrote:
>>
>> Surprisingly enough, what Charig (1985:26) actually wrote was "Let us
>> define a class Aves as the clade that is demarcated from its
>> antecedents by the appearance of the evolutionary novelty ‘feathers’"
>> (quoted from Senter 2005:4).
>>
>> So, yeah, an explicit clade definition.  Albeit not a very good one.
>
> Yes, note that it lacks a species or specimen to anchor the apomorphy
> to. Given that "feather" can refer to non-homologous structures in
> other organisms (e.g., http://en.wikipedia.org/wiki/Feathering_(horse)
> ), it's potentially meaningless. (Although a reasonably charitable
> interpretation would make it synonymous with _Avipinna_.)
>
> --
> T. Michael Keesey
> http://tmkeesey.net/
>