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Re: Greg Paul is right (again); or "Archie's not a birdy"
evelyn sobielski <firstname.lastname@example.org> wrote:
> And of course, Neornithes = crown birds is perhaps the only higher-level
> definition in this whole mess that is stable and widely accepted; even those
> who synonymize it with Aves do not argue about its
> content. On the contrary, a major argument for Aves = Neornithes seems to be
> the robustness of this clade.
Actually, the vaunted "stability" of Neornithes came about more by
accident than design. It has a checkered history, just like
Ornithurae and Aves.
Neornithes was originally proposed (by Gadow, 1892) as a substitute
for Ornithurae. Because Gadow included _Ichthyornis_ and
_Hesperornis_ in his Neornithes, and because these two were thought to
belong inside the crown clade, Neornithes came to be applied to the
crown clade. Although _Ichthyornis_ and _Hesperornis_ were later
removed from the crown clade, the name Neornithes remained attached to
the crown clade, and it's pretty much been stuck there ever since.
I like Gauthier and deQueiroz's (2001) proposal that Neornithes become
a more inclusive clade than the crown, such as a node-based clade that
contains _Hesperornis_ and modern birds.