RE: Feduccia in _PNAS_

[Tim Williams <twilliams_alpha@hotmail.com>]

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.

Cheers

Tim