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Re: Greg Paul is right (again); or "Archie's not a birdy"

David Marjanovic <david.marjanovic@gmx.at> wrote:

> And why not include Enantiornithes in Aves? Remember that there are several
> pretty obvious ornithothoraceans of which it is not clear whether they are
> enanti- or euornitheans: *Eoalulavis*, *Eoenantiornis*, *Liaoningornis*,
> *Aberratiodontus*...

The hideously-named _Aberratiodontus_ is most probably a junior
synonym of _Yanornis_ (Zhou et al., 2008).  That would make it a
card-carrying eurornithean.

evelyn sobielski <koreke77@yahoo.de> wrote:

> True, but I was not considering etymology: if the supposed apomorphies on 
> which a phylogenetic hypothesis rests turn out to be homoplasies, the clades 
> named from this hypothesis are affected.

I wouldn't have thought so.  A name persists even if it the apomorphy
after which it was named is subsequently shown to be homoplastic,
and/or have a wider distribution.  For example, Carinatae originally
began as the counterpoint to Ratitae within the crown clade, because
carinates have a keel ('carina') on the sternum, but ratites have a
sternum that is flat, like a raft ('ratum').  Later (much later) the
name Carinatae was co-opted by Cracraft (1986) for a much larger group
of birds that included _Ichthyornis_ and Neornithes (the crown clade).
 But we now know that the presence of a sternal keel is synapomorphic
of a much larger clade than this.

> Ornithothoraces uses an enantiornithine and a neornithine. The instability of 
> basal Pygostylia and the physical constraints for self-powered flight make me 
> wary of whether enantis and euornis are
> sisters.
> Their shoulder and ankle bones evolved independently to the respective 
> apomorphic condition. The sterna are different enough except for the keel. 
> There is no reason to assume that the pygostyle is a
> synapomophy either. All this indicated that the "basal ornithothoracine" was 
> barely capable of self-powered flight, if at all.

You may well be correct on all these points.  However, clades
Pygostylia and Ornithothoraces will endure even if the contents of
these clades change, or the phylogenetic brackets associated with
individual apomorphies (or inferred behaviors based on these
apomorphies) change.  Euornithes and Enantiornithes will remain sister
taxa because they are mutually defined as such: _Passer domesticus_
but not _Sinornis santensis_ vs > _Sinornis santensis_ but not _Passer