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Apomorphy-based Names (Was Re: begging...)



David Marjanovic (david.marjanovic@gmx.at) wrote:

<"The origin of Avebrevicauda", however, would be a paper that searched
for the sistergroup and maybe 2nd outgroup of Avebrevicauda, as well as
describing & discussing the latter's oldest fossils.>

  Though I agree in general with both Paul, 2002 and de Quieroz and
Gauthier, 2001 on some things phylogenentic, I must say that
apomorphy-based nomenclature is based on their features, and a clade like
Avebrevicauda is not the same as Tyrannosauridae in general form,
irrelevant of their phylogenetic positions. It is impossible to know which
bird among Aves have such an homologous structure as to apply in this
sense. Paul named Avebrevicauda for Aves which have ten or fewer free
caudals, but what of birds which lack this, and suggest that the descent
of any bird with less than 10 free caudals derived from an ancestor with
more than 10?

  Anyways, the origin of Avebrevicauda would require a developmental and
biologically evolutionary explanation, not a phylogenetic one, because its
very basis and nature is not stable. de Quieroz and Gauthier refined the
apomorphy-based clade to require a select species upon which the condition
named could be encountered and then tranced backwards; that of Paul maps a
generality that must be followed forward.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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