birds and avians again

["T. Mike Keesey" <tmk@dinosauricon.com>]

On Fri, 31 Aug 2001 Dinogeorge@aol.com wrote:

> In a message dated 8/30/01 11:36:22 PM EST, qilongia@yahoo.com writes:
>
> << This does not seem to be a matter of "educating the public" but rather a
> matter of establishing all stems based on only the living members, which
> contradicts the fossil inclusion.... It is doubtful anyone would use the
> redefinitions in such a manner. >>
>
> I see nothing contradictory in the system I outlined. What could be simpler?
> If it's more closely related to modern birds than to any other animals, why
> not call it a bird (or, if you like, bird sensu lato)?

"Bird" is a vernacular English term and hence its usage is dictated by the
English-speaking public at large. I think it's pretty clear that most
types of dinosaur do not fall under the common usage of "bird".

You'd do better to try and make a case for "avian", which is based on a
formal taxon. But, since, as you pointed out, this term and others were
originally coined for extant animals, shouldn't it make greater aesthetic
sense to restrict them to node-based clades specified by extant animals?
This is far more in line with the original usage (not to mention the
popular usage!).

Furthermore, I don't think aesthetics should be the only concern here. For
well over a century, _Aves_ has referred to a fairly specific monophyletic
group including _Archaeopteryx_ and modern birds (despite one attempt,
made with aesthetic intentions, to make it a crown clade). Of course there
are instances where traditional usages may need emending, but aesthetics
should be balanced with stability. This is a natural, monophyletic group
which has gone by the same name for a very long time -- why disrupt that?
And, if it is to be disrupted, why on Earth would you make it stem-based?

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T. MICHAEL KEESEY
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