RE: Giant \"Ducks\"

[Tim Williams <twilliams_alpha@hotmail.com>]

> http://www.washington.edu/burkemuseum/events/duck/

"Mihirungs were a unique group of Australian flightless birds also known as 
?thunderbirds? and were derived from early waterfowl (ducks, geese, and 
swans)."

I believe the idea that dromornithids (mihirungs) are derived from waterfowl 
("Anseriformes") stems from Murray and Megirian (1998), and later research 
by Vickers-Rich and others.  This overturned the long-held belief that 
dromornithids were ratites.  "Magnificent Mihirungs: The Colossal Flightless 
Birds of the Australian Dreamtime." is the most comprehensive treatment of 
this group to date, even though certain aspects of the volume came under 
withering criticism from Olson (2005).

Murray, Megirian, and Vickers-Rich propose that the dromornithids belong 
within the Anseriformes, close to the extant Anhimidae (screamers).  The 
"giant duck" thing is a little misleading, considering that these authors 
align mihirungs with screamers (both phylogenetically and 
ecomorphologically), rather than waterfowl like ducks.  There is some 
controversy over just how close dromornithids are to anseriforms, and 
whether or not the first anseriforms were filter-feeders (like most modern 
anserines) or macrofeeders (like screamers and the magpie goose... and 
mihirungs, if they are true anseriforms).  Wroe (1998) certainly believes 
the mihirungs to be carnivores.

Some dromornithids were not all that large, like the cassowary-sized 
_Barawertornis tedfordi_.  On the other hand, _Dromornis stirtoni_ may have 
been the heaviest bird ever (maybe weighing in 500 kg, and about 3m tall), 
so the "giant" part of "giant duck" is appropriate for this guy (and several 
other dromornithid species).

References

Murray, P.F. and Megirian D. (1998) - The skull of dromornithine birds: 
anatomical evidence for their relationship to Anseriformes. Records of the 
South Australian Museum, 31: 51-97.

Olson, S.L. (2005).  "Magnificent Mihirungs.  The Colossal Flightless Birds 
of the Australian Dreamtime."  The Auk: 122: 367?371.

Wroe, S. (1998).  Bills, bones and bias: did thunder birds eat meat? 
Riversleigh Notes 40: 2-4.