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side-note -- Re: 11th specimen of Archaeopteryx



Trying this one more time, sorry if this is a multi-post...

It's not a perfect analogy, but think of this in terms of how the term
'planet' was defined a few years ago.

If you asked an astronomer in 2005 whether or not Eris was a planet,
the answer would be that it depended on what you meant when you said
"planet," which had no formal definition outside convention. This is
equivalent to "avian" now. Is *Archaeopteryx* an avian? Impossible to
say because nobody can agree what that word even means.

Someday the Phylocode will define the word for us. Will everyone agree
to follow that definition? Probably not, just as not all astronomers
accept the IAU definition of planet. But at least it's something
concrete.

The next step will be figuring out whether or not *Archaeopteryx*
meets the parameters of the definition or not. Depending on where the
boundary is set, this may be controversial for decades if not
centuries, given shifting phylogenetic positions.

But, that's all about "avian," not "bird". There will never be a
universal definition of "bird," outside the dictionary definition,
though those often hinge on the scientific definition. This is from
the OED online:

Bird:
"Any feathered vertebrate animal: a member of the second class (Aves)
of the great Vertebrate group, the species of which are most nearly
allied to the Reptiles, but distinguished by their warm blood,
feathers, and adaptation of the fore limbs as wings, with which most
species fly in the air."

Is *Archaeopteryx* a bird in this definition? It seems to define the
"Class Aves" as any vertebrate with the following characteristics:
1. endothermic (probably to some degree)
2. feathers (check)
3. wings (check)

So, according to the OED definition *Archaeopteryx* is a bird and no
phylogenetic shifts can change that. It is also a member of the "Class
Aves" but, not necessarily of the clade Aves. Note that under this
definition, *Microraptor* and presumably all aviremigians are also
"birds", because it says that "wings" are not necessarily used in
flight.

But, again, this is a layman's definition of a colloquial term, not
something scientific.

Matt