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Re: Avian Ancestors, new book on theropods

On Thu, Feb 28, 2013 at 6:15 PM, Tim Williams <tijawi@gmail.com> wrote:
> Thus, subsequent studies have disagreed over whether Avialae is
> stem-based (including crown birds, excluding dromaeosaurids) or
> node-based (including _Archaeopteryx_ + crown birds).

Don't forget that it was also defined as apomorphy-based: "'Avialae'
refers to the clade stemming from the first panavian with feathered
wings homologous (synapomorphic) with those of Aves (Vultur gryphus
Linnaeus 1758) and used for powered flight"  (Gauthier and de Queiroz

That definition makes the inclusion of Archaeopteryx rather ambiguous.
But the intent was to provide a name for a clade that everyone's
interested in over a clade with stable composition.

T. Michael Keesey