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Re: BFC Epiphany



Although I enjoyed the rest of this satirical post...

On 9/26/07, Mike Taylor <mike@indexdata.com> wrote:
>
> (George cheats a bit here: he calls all dinosaurs

[except birds]

> stem-birds because
> birds are extant, if I understand the reasoning properly.  But I
> don't think that kind of blatant extantism has any place in an
> enlightened society :-)

Well, since most (all?) people don't use "bird" for the crown group
(including Olshevsky), it's more volantism than extantism. But there's
nothing wrong with using "stem-avian" to indicate all non-avian
pan-avians (using _Aves_ as a crown group). It's a convenient
shorthand for referring to an extinct, paraphyletic group
characterized by a our knowing less about their soft tissue, behavior,
diversity, etc. (Although it includes more than just non-avian
dinosaurs, such as "lagosuchids" and [probably] pterosauromorphs.)

The only real problem is that sometimes "stem-" is used in a somewhat
different way. Instead of being used to refer to a total group minus
its corresponding crown group, it's sometimes used to refer to a crown
group minus its subordinate crown groups. In that usage, "stem-avian"
would mean all crown avians except for those in the paleognathe and
neognathe crown groups. Hopefully one usage wins out for consistency.
(I personally prefer the former, but....)

-- 
Mike Keesey