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SOUTHERN ANSERIFORMS & NEW ish ARCHAEOPTERYX
Joao Simoes Lopes Filho sent this email some time ago - I meant to reply
to it sooner, sorry. Joao asked...
> Is there some support for (Neo-)Gondwanan origin of Anseriformes( and
> probably Galloanserae) ?
Yes, phylogenetic studies certainly indicate that Anseriformes
originated in the Southern Hemisphere as virtually all basal taxa are
southern (Anhimidae and Anseranatidae). Anatids probably also
originated in the south seeing as dendrocygnines (_Dendrocygna_ +
_Thalassornis_), cnemiornithids, _Cereopsis_ and other basal taxa are
southern (Livezey 1995, 1996). Worthy et al. (1997) argued that
_Cereopsis_ and _Cnemiornis_ form a clade within Anserinae (Livezy
always regards cnemiornithids as basal anatids I think - I don't have the
papers to hand) but this doesn't affect the strong southern signal in the
tree. Northern radiations of anatids, like _Anser_, _Branta_ and the
_Olor_ group swans are therefore members of clades whose basal taxa
Cracraft has argued that Galliformes are also ancestrally southern - this
would support a southern origin for Galloanserae - but the absence of
any comprehensive phylogenetic analysis of the galliforms means that
this is untested (AFAIK).
There are a few fossils that might confuse this picture however. Olson's
(1999) suggestion that _Anatalavis oxfordi_ is an anseranantid was
discussed here recently (it has been contested by Dyke (2000 and in press)
- if Olson is right then anseranatids are not endemic to the Southern
Hemisphere. Feduccia (1996) mentions some supposed Northern
records of anhimids - these are unpublished and unconfirmed AFAIK.
_Presbyornis_, the sister-taxon to Anatidae within the Anatoidea (as
per Livezey 1997), is a Northern Hemisphere taxon however
(notwithstanding possible Antarctic records), so further study is
required to determine whether anatoids actually originated in the North
(in which case anatids may still have arisen in the South...), or if
_Presbyornis_ represents a separate Northern invasion.
> What is the zoogeographical explanation of presence of Black Swan in
> Australia (Cygnus ater) and Black-necked Swan in South America (Cygnus
> melanocoryphus). And Brazilian "Coscoroba" (Coscoroba coscoroba)...is
> it a primitive swan?
_Coscoroba_ would appear to be the most basal swan. Among
_Cygnus_, _atratus_ and _melanocoryphus_ are the most basal, and
were found to be sister taxa by Livezey (1996) (he didn't code _C.
sumnerensis_ but I think there is general agreement that this is closest
to _C. atratus_). The _Olor_ swans would therefore appear to
represent a Northern radiation of a clade that originated in the South.
I can dig out the refs if they're needed.
Oh yeah, new _Archaeopteryx_ (Vol. 18) has arrived. Includes the
Frey, E. and Tischlinger, H. 2000. Weichteilanatomie der
Flugsaurierfusse und Bau der Scheitelkamme: Neue Pterosaurierfunde
aus den Solnhofener Schichten (Bayern) under der Crato-Formation
(Brasilian), pp. 1-16.
As it says. Lots of pretty pictures of the _Pterodactylus_ with the soft
tissue head crest, new WWD-style tapajerids and the Crato Fm
azhdarchid with the curved foot claws, scaly sole pad etc.
Videler, J. J. 2000. _Archaeopteryx_: a dinosaur running over water?
Videler suggests that _Archaeopteryx_ might have behaved like extant
_Basiliscus_. No way, there are fundamental flaws in the reasoning.
Suggests that the manual claws could have snapped up and down on
the distal tip of the phalanx in a way that is anatomically impossible.
Naish, D. 2000. Theropod dinosaurs in the trees: a historical review of
arboreal habits amongst nonavian theropods. pp. 35-41.
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