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Senter, 2005 and the definition of _Aves_



(cross-posted to the Dinosaur Mailing List and the PhyloCode Mailing List)

Senter's recent paper on archosaurian phylogenetic taxonomy makes the
following claim:

"If the PhyloCode is published, gains acceptance, and continues to
recognize apomorphy-based phylogenetic definitions, the valid
phylogenetic definition of Aves will be the apomorphy-based definition
of Charig (1985), which ties the name Aves to the origin of feathers."
(2005:4)

Charig's definition is listed as:

"Let us define a class Aves as the clade that is demarcated from its
antecedents by the appearance of the evolutionary novelty 'feathers.'"
(1985:26)

Senter is invoking the draft PhyloCode's rules on precedence (Art.
12), but it seems to me that he is overlooking Articles 7.1 and 7.2 of
the draft PhyloCode:

"7.1. Establishment of a name can only occur on or after 1 January
200n, the starting date for this code.
"7.2. In order to be established, a name of a taxon must: (a) be
published as provided for by Article 4; (b) be adopted by the
author(s), not merely proposed for the sake of argument or on the
condition that the group concerned will be accepted in the future; (c)
comply with the provisions of Articles 7 and 9-11; (d) be registered
as provided for in Article 8, and the registration number be cited in
the protologue; and (e) comply with the provisions of Article 17."
(Cantino and de Queiroz, 2003)

Furthermore, Charig's definition doesn't tie the character to a
particular specimen or species, so it seems to me that the form is
invalid, anyway. Feathers luckily happen to be a unique trait (as far
as we know), but, e.g., defining Mammalia as the clade demarcated from
its antecedents by the appearance of the evolutionary novelty 'hair'
would be nonsensical, since several clades have independently evolved
hair. Gauthier and de Queiroz' definition of _Avifilopluma_ is a
proper apomorphy-based clade definition, since it includes a species
specifier: "the clade stemming from the first panavian with feathers
homologous (synapomorphic) with those of _Aves_ (_Vultur gryphus_
Linnaeus 1758). 'Feathers' here refers to hollow-based, filamentous,
epidermal appendages produced by follicles" (2001:25). Would PhyloCode
accept Charig's definition even if it did cover unregistered taxa
published before its starting date?

REFERENCES:

- Cantino, P. D. and K. de Queiroz. 2003. PhyloCode: a phylogenetic
code of biological nomenclature [online paper]. Version 2. Ohio Univ.,
Athens, Ohio. [updated 1 August 2004]. Available at
http://www.ohiou.edu/phylocode/.

- Charig, A.J. 1985. Analysis of the several problems associated with
_Archaeopteryx_. Pages 21â31 in M. K. Hecht, J. H. Ostrom, G. Viohl,
and P. Wellnhofer (eds.). The Beginnings of Birds.Freunde des
Jura-Museums, EichstÃtt.

- Gauthier, J. and K. de Queiroz. 2001. Feathered dinosaurs, flying
dinosaurs, crown dinosaurs, and the name "Aves". Pages 7â41 in New
perspectives on the origin and early evolution of birds: proceedings
of the international symposium in honor of John H. Ostrom (J. Gauthier
and L. F. Gall, eds.). Peabody Mus. Nat. Hist., Yale Univ.

- Senter, P. 2005. Phylogenetic taxonomy and the names of the major
archosaurian (Reptilia) clades. PaleoBios 25(2):1â7.

--
Mike Keesey
The Dinosauricon: http://dino.lm.com
Parry & Carney: http://parryandcarney.com