Re: birds and avians again

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

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

> In a message dated 8/31/01 1:54:24 PM EST, tmk@dinosauricon.com writes:
>
> << "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". >>
>
> This is merely a historical accident that I think should be rectified.

Vernacular language isn't something you rectify -- it just is. Taxonomists
only have control over formal taxa and their vernacular forms. Words like
"bird", "turtle", etc. are purely vernacular and you can't really mandate
how they are used (in fact, I think "turtle" is used a bit differently in
Britain than in North America, isn't it?). If someone appoints you Emperor
George you can decree that all English-speaking peoples call _Stegosaurus_
a bird, but until then I think you are going to be frustrated.

> As far as formal naming of these groups goes, one could stick with a
> node-based Aves (Latin root "birds") for the clade including and
> descended from the last common ancestor of Archaeopteryx and modern
> birds, a la Linnaeus,

Linnaeus never knew of _Archaeopteryx_. Would it be _sensu_ Meyer? Anyway,
I agree with the rest of this.

> and then name the more inclusive stem-group birds Ornithes (Greek root
> "birds").

But it's already been named at least thrice over -- _Ornithosuchia_ (which
could not be used by PhyloCode rules, since excludes the eponymous genus
_Ornithosuchus_), _Ornithotarsi_ (my personal favorite), and
_Avemetatarsalia_. _Dinosauromorpha_ may term this clade, too, if Dave
Peters is right about pterosaurs not being archosaurs, and
_Dinosauromorpha_ is redefined to specifically exclude _Crocodylus_.

> (But I don't like pinning a major group like Aves to a single genus
> such as Archaeopteryx: if we find a slightly pre-archaeopterygid
> fossil flying bird, why arbitrarily exclude it from Aves?)

Because you have to cut it off somewhere. Formal taxa are supposed to have
clear boundaries -- something belongs, or it does not, no halfway.
(Vernacular terms like "bird" are often different in this respect,
though.) And we can't anchor a clade on something we haven't discovered!

> The other extant archosaur crown group would
> retain the familiar node-based name Crocodylia,

Agreed.

> and the more inclusive stem-group crocodiles (all archosaurs more
> closely related to Crocodylia than to Ornithes) would become Suchia.

That name's already been assigned to Clade(_Stagonolepis_ + _Crocodylus_),
I think. Otherwise it's not a bad idea -- a much better name for it than
_Pseudosuchia_, although _Crocodylotarsi_ is also not a bad name.

> The vernacular, paraphyletic term "dinosaurs" would then denote the
> non-avian ornithans.

"Dinosaur" isn't a purely vernacular term, though -- it's based on a
formal taxon. Using the vernacular and formal versions differently is
inviting a world of confusion.

(Wouldn't it be "ornitheans" or "ornithines"?)

I kind of like using "dino" for the pure vernacular.

> The more I examine this system, the better I like it.

Well, I like it better than the last one you posted.

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T. MICHAEL KEESEY
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