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Re: Greg Paul is right (again); or "Archie's not a birdy"



Mike Keesey <keesey@gmail.com> wrote:

> Could I convince biologists to avoid the term "bird" and use an
> appropriate alternative (avian, ornithuran, avialan, avipinnan, etc.)
> in technical discussions? (Or at least clarify what they mean by
> "bird"?)

Good luck with that :o)

De Queiroz (2007) had a similar proposal: to add various modifiers to
the name "birds" and this way make them equivalent to not one, but
several formal names. "Feathered birds" would be equivalent to
_Avifilopluma_, "winged birds" to _Avialae_ (sensu Gauthier & de
Queiroz 2001) etc. According to the author, "whether a particular
fossil is or is not a bird [could] no longer be reduced to a simple
yes or no question". Is _Archaeopteryx_ a bird? Well, it was
definitely a pan-bird and a feathered bird, but it was not a
short-tailed bird and we are currently not sure whether it was a
flying bird.

This solution has its drawbacks, however. The idea seems to be that
"birdness" gradually increases towards the crown and that "side
branches" of avian tree have no right of apomorphies of their own. For
example, "toothless birds" is a shortcut for "the most inclusive clade
exhibiting toothless jaws synapomorphic with those in _Vultur gryphus_
Linnaeus 1758". _Confuciusornis_ was toothless, but its absence of
teeth was homoplastic with that in _Vultur gryphus_.

> The crown group is far more robust and far more significant.

Significant, yes, but robust? I don't think its composition is
particularly stable (from the standpoint of fossils, of course -- from
the standpoint of living taxa, anything between the crown and its
total clade is equally stable) and there are probably clades
diagnosable by a larger number of morphological apomorphies.

evelyn sobielski <koreke77@yahoo.de> wrote:

> Given that Ornithurae rests on a highly autapomorphic stem clade 
> (Hesperornithes), the plesiomorphic part of which remains entirely unknown, 
> and given the general lack of known basal diversity in Ornithuromorpha, the 
> appropriateness of distinguishing between Ornithurae vs Ornithuromorpha vs 
> Euornithes cannot at present be rigorously determined.

"Appropriateness"? _Ornithurae_, _Ornithuromorpha_, and _Euornithes_
all have different definitions and composition. Even if there were no
known differences in composition, it would not be a problem; but we
know of possible non-ornithuromorph euornithines (_Archaeorhynchus_ in
O'Connor & Forster 2010, You et al. 2010) and non-ornithuran
ornithuromorphs (many of them, actually: _Patagopteryx_,
hongshanornithids, ...).

> Of the definitions of Aves listed at 
> http://www.taxonsearch.org/dev/taxon_edit.php?Action=View&tax_id=43, most are 
> problematic because of the reliance on Archie and/or the likely 
> nonmonophyletic "Ratitae".

Polyphyly of ratites is hardly a problem. The PhyloCode requires using
"species"* as specifiers. "Higher taxa" may be used only "to clarify
the phylogenetic position of a specifier" (Note 11.1.2).
_Palaeognathae_ would surely be a better clarification, however.

*I don't like the term "species". I'm with Mishler on this one: the
species rank must go the way of all others.

> Hence, if we'd need a phylogenetic definition of Aves RIGHT NOW, the only one 
> that pertains to a clade that is proven beyond all reasonable doubt, and to a 
> clade interesting enough to warrant such a familiar name, and that is not 
> wrought with a whole damn lot of controversy, would be:
> "Anything closer to _Struthio camelus_ + _Vultur gryphus/Passer 
> domesticus/Gallus gallus_ than to _Enantiornis leali_ + _Sapeornis 
> chaoyangensis_ + _Confuciusornis sanctus_"
> or equivalent.

That's _Euornithes_. Do you really think this is the clade that most
deserves the name _Aves_? I mean, the known composition of the clade
in question is equivalent to something like (_Archaeorhynchus_ +
_Neornithes_). What is so important about it? What significant
apomorphies do we currently believe originated there?

BTW, using _Gallus gallus_ as a default representative of living birds
in phylogenetic definitions is a great idea. It is still relatively
deeply nested, we know its phylogenetic position with great precision
(unlike _V. gryphus_ and _P. domesticus_) and as a model organism for
evo-devo it is very well studied.

References:


de Queiroz K 2007 Toward an integrated system of clade names. Syst
Biol 56(6): 956-74

Gauthier JA, de Queiroz K 2001 Feathered dinosaurs, flying dinosaurs,
crown dinosaurs, and the name "Aves". 7-41 in Gauthier JA, Gall LF,
eds. New Perspectives on the Origin and Early Evolution of Birds:
Proceedings of the International Symposium in Honor of John H. Ostrom.
New Haven: Yale Univ Press

O'Connor PM, Forster CA 2010 A Late Cretaceous (Maastrichtian)
avifauna from the Maevarano Formation, Madagascar. J Vert Paleont
30(4): 1178--201

You H-L, Atterholt J, O'Connor JK, Harris JD, Lamanna MC, Li D-Q 2010
A second Cretaceous ornithuromorph bird from the Changma Basin, Gansu
Province, northwestern China. Acta Palaeont Pol 55(4): 617-25
-- 
David Černý