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RE: Feduccia in _PNAS_
Christopher Taylor wrote:
AT the risk of a little pedantry, Clarke and Norell suggested that some of
the characters usually regarded as 'enantiornithine' might be more
widespread among basal birds. So, while they probably didn't doubt the
monophyly of the main Enantiornithes clade, they did object to less
well-known species being assigned to Enantiornithes by a few 'signature'
characters without an explicit phylogenetic analysis.
Well... in Clarke and Norell's own words:
"While 27 characters have been proposed as derived morphologies of
Enantiornithes (e.g., Walker, 1981; Chiappe, 1991, 1996, 2001; Kurochkin,
1996; Sereno et al., 2002; listed in the supplementary information of Norell
and Clarke, 2001), in the current analysis, only 4 characters support
monophyly in both most parsimonious trees. The strict consensus of these is
presented in figure 24. Enantiornithine monophyly collapses with a tree
length one step longer than the most parsimonious topologies."
Given that Clarke and Norell used four fairly representative taxa
(_Gobipteryx_, _Neuquenornis_, _Concornis_, _Cathayornis_) for
Enantiornithes in their analysis, even the monophyly of a 'main
Enantiornithes clade' seems shaky - at least according to that analysis.
Also, Sereno (2005) defined Enantiornithes as the most inclusive clade
containing _Sinornis santensis_ but not _Passer domesticus_. This is
perhaps not the ideal definition of Enantiornithes, given that the eponymous
taxon (_Enantiornis_) is excluded from the definition. Nevertheless the
monophyly and/or composition of Enantiornithes hinges on the position of
_Sinornis_ under this definition.