Re: THAT DUCK-CHICKEN THING

[Ronald Orenstein <ornstn@home.com>]

>Feduccia's early work on this issue was of rather different stuff than 
>his later work.  He argued for a special common ancestor for 
>Anseriformes and Phoenicopteriformes with _Presbyornis_ on the way to 
>both groups (or flamingos?) if I recall correctly. 

You may be thinking of Juncitarsus, which Olson and Feduccia consider a
"shorebird-flamingo mosaic" (see Feduccia's book at p. 208), a view
supported by Stefan Peters.

>Olson has also been critical of Cracraft because Cracraft uses the 
>opposite extreme; determining relationships from superficial and mildly 
>similiar characters.  View Cracraft's masterpiece (in bad cladistic 
>analysis) of ratite phylogeny.  

Not to mention his suggestion that loons, grebes and hesperornithiforms
were related (though that was a while back.....)

>I can concede that the retroarticular processes are similiar in the two 
>groups and they are possibly some of the best evidence for the 
>'duck-chicken' relationship in the sarcastic Olson and Feduccia sense.  
>However, as noted, these differ in the details and if I remember 
>correctly (somebody, confirm or deny) diatrymid retroarticular processes 
>do not show compression and similiar details.  However, I would not 
>place much stock in this argument for diatrymids are relatively 
>specialized birds.

Without checking specimens, let me remind you that the retroarticular
process serves, among other things, as the insertion point for m. depressor
mandibulae, the chief jaw-opening muscle in birds.  Birds which open their
mouths against force may have large, well-developed processes.  You can see
this in filter-feeders like flamingos, or in birds that use the beak for
"gaping" - that is, spreading apart materials to expose food.  Meadowlarks
have a pretty big process, for example, and use it to spread vegetation
apart on the ground as they forage, and the South American Scarlet-headed
Blackbird, or "Federal", which uses a beak like a chisel to split open
thick-stemmed bulrushes, has an immense process approaching that of a
flamingo in proportion.  IOW, beware of convergence! 
  
>I think that the OTHER Olson and Feduccia paper in 1980 on the 
>recurvirostrid relationship of phoenicopterids, nicely domolished this 
>notion.  

Ah.  This is, of course, the Juncitarsus paper.  I confess, though, I am
not so sure about comparing flamingos to the living Banded Stilt, a
communal breeder with somewhat flamingo-like behaviour that is surely a
case of convergence.  The fossil evidence is interesting, though.

--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
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