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RE: Giant \"Ducks\"




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.