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[firstname.lastname@example.org: Swans: taxonomy and phylogeny]
Forwarded on behalf of HP (retired) Darren Naish, who really ought to
shut up writing about swans and work on his Damned Dissertation.
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Date: Thu, 14 Jul 2005 02:03:08 +0100
From: "Toni" <email@example.com>
To: "Mike Taylor" <firstname.lastname@example.org>
Subject: Swans: taxonomy and phylogeny
Hi Mike. If it's not too much trouble to ask, you could please fwd the
following to DML for me? It concerns one of your favourite subjects: extinct
members of Anseriformes :)
On fossil swans and the affinities of the new taxon _Afrocygnus chauvireae_,
Christopher Taylor wrote...
'all swan genera'? Are there any others other than _Cygnus_, this new genus
(which sounds to be doubtfully distinct from _Cygnus_), and _Coscoroba_? Is
_Coscoroba_ even currently regarded as the sister taxon to _Cygnus_? Sounds
like a bit of an over-classification to me.
Well, it isn't an over-classification made by Louchart et al. 2005 as this
classification was already in place: I assume Louchart et al. are using
Livezey's taxonomy (Livezey 1996, 1997) - itself based on that of Vigors 1825
and other authors - where Cygnini includes Coscorobina and Cygnina, and
_Cygnus_ consists of the subgenera _Chenopsis_, _Cygnus_ and _Olor_. Worthy et
al. (1997) treated the goose-swan clade as a 'tribe' (rather than a
'subfamily', as per Livezey), and thereby demoted it from Anserinae to
Anserini, and thereby demoted swans to the 'subtribe' Cygneae.
And are there swan taxa in addition to _Coscoroba_ and _Cygnus_? Yes indeed
there are; _Cygnopterus_ Lambrecht, 1931 from Oligocene Belgium; _Cygnavus_
from Miocene Germany and France and Oligocene Kazakhstan; _Cygnanser_ Kretzoi,
1957 from Pliocene Hungary; _Guguschia_ Aslanova & Burchak-Abramovich, 1968
from the Oligocene of Azerbaijan; and _Megalodytes_ Howard, 1988 from the
Miocene of California, and probably the Miocene of Japan. There might be
others. As for what these taxa really are, while it has been stated that some
are not complete enough for phylogenetic assignment (Livezey 1997, p. 469),
most seem enough like _Cygnus_ to be members of Cygnina: those that are
outdoubted swans (e.g. the flightless _Megalodytes_) seem to have not yet been
intrepreted within the context of the coscorobin-cygnin dichotomy. I say all
this without having yet seen Louchart et al. of course. Mlíkovský (2002)
suggested that _Cygnavus_ might be a dendrocygnine, but then.. Mlíkovský
awful lot of things.
Refs - -
Livezey, B. C. 1996. A phylogenetic analysis of geese and swans (Anseriformes:
Anserinae), incuding selected fossil species. _Systematic Biology_ 45, 415-450.
- - . 1997. A phylogenetic classification of waterfowl (Aves: Anseriformes),
including selected fossil species. _Annals of Carnegie Museum_ 66, 457-496.
Mlíkovský, J. 2002. _Cenozoic Birds of the World. Part 1: Europe_. Ninox Press
(Praha), pp. 406.
Worthy, T. H., Holdaway, R. N., Sorenson, M. D. & Cooper, A. C. 1997.
Description of the first complete skeleton of the extinct New Zealand goose
_Cnemiornis calcitrans_ (Aves: Anatidae), and a reassessment of the
relationships of _Cnemiornis_. _Journal of Zoology_ 243, 695-723.
School of Earth & Environmental Sciences
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