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Re: Sapeornis and other Mesozoic Birds

On 9/13/06, Roberto Takata <rmtakata@gmail.com> wrote:

*The clade stemming from the most recent common ancestor of _Struthio camelus_ and _Passer domesticus_.

Was this as an example or an actual proposed definition? Essentially

*The clade stemming from the first vertebrate to evolve fligth
feathers and wings.

This does not pass PhyloCode muster, since it lacks any mention of a species or specimen.

"1.1. Specifiers are species, specimens, or apomorphies cited in a
phylogenetic definition of a name as reference points that serve to
specify the clade to which the name applies. All specifiers used in
node-based and branch-based definitions of clade names, and one of the
specifiers used in apomorphy-based definitions of clade names, are
species or specimens. The other specifier used in an apomorphy-based
definition of a clade name is an apomorphy."

It is close to Gauthier and de Queiroz' (2001) definition of Avialae,
which does follow PhyloCode rules: "The clade stemming from the first
panavian with feathered wings homologous with those of Aves (Vultur
gryphus) and used for powered flight."

The problem with Benton's form is that if some other vertebrate group
developed flight feathers and wings convergently with those of
avialans, and the other group developed them first, the content would
completely shift. Gauther and de Queiroz' definition, OTOH, is linked
to a specific taxon (Vultur gryphus) which it can never exclude.
T. Michael Keesey
The Dinosauricon: http://dino.lm.com
Parry & Carney: http://parryandcarney.com