Re: Microraptor and Birds

["T. Michael Keesey" <mightyodinn@yahoo.com>]

--- Dino Guy Ralph <dinoguy@sbcglobal.net> wrote:
> How are Aves and Avialae currently defined?  Is either clade closer to
> synonymy with the colloquial term, "bird"?

There are a couple definitions in existence for both of them.

Gauthier 1986 used _Aves_ as a crown clade (equivalent to _Neornithes_), and
coined _Avialae_ for the clade including _Archaeopteryx_, corresponding more
closely to the traditional usage of Classis Aves.

Needless to say, excluding such forms as _Ichthyornis_, _Hesperornis_, etc.
from _Aves_ has not proven terribly popular, although there is a philosophy
behind it.

Padian 1997 redefined _Aves_ as a node-based clade (_Archaeopteryx_ + modern
birds) equivalent to Gauthier's _Avialae_, and then redefined _Avialae_ as a
stem-based clade (modern birds <- _Deinonychus_).

Since the colloquial term "bird" is rarely applied to anything extinct except
by paleontologists, I think it's kind of hard to say which clade it most
closesly corresponds to. I would view "bird" as a fuzzy kind of vernacular term
-- some things are definitely birds, some things definitely aren't, and some
things make you scratch your head a bit.

(I might also mention Ax' extremely broad stem-based _Aves_, including all
dinosaurs, "lagosuchians", and pterosaurs [assuming they are archosaurs].
Equivalent to de Queiroz and Gauthier's _Panaves_.)

> Now, on to _diagnosis_.

Someone else will have to address this.

=====
=====> T. Michael Keesey <keesey@bigfoot.com>
=====> The Dinosauricon <http://dinosauricon.com>
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