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Re: emu History

>My name is Nancy Cavanaugh. I am currently writing a book about the emu. >In doing my research I have found some discrepancies about when they >appeared on Earth.

>The commonest answer is 80 million years ago, which from my reading was
>determined in 1971 (or was it in 1973? the research I've done indicates
>both years) by Joel Carcraft. Today, however, I tripped across a site
>that said they couldn't have arrived before 45 million years ago, which
>was backed by reasonably solid scientific reasoning.

>Which is the correct date? Who is this date attributable to? What
>evidence do they use for this date?

>Nancy Cavanaugh

The oldest emu-like bird is the Late Oligocene Dromuarius gidju, which is probably close to the common ancestor of Emus and Cassowaries, and "Dromuarius" guljaruba of approximately the same age, but apparently somewhat more emu-like, so presumably the Emuine line separated from the line leading to the cassowaries before this time. Whether the common ancestor arrived in Australia flying or walking is anybody's guess. If the latter it could hardly have happened later than the Eocene when Australia separated from Antarctica.

>That said, and noting that Joel's name is "Cracraft", the Handbook of the
>Birds of the World, Volume one, published in the 1992, notes that the
>oldest fossils that can be ascribed to the living genus of emus are only
>some 5000 to 10,000 years old, and belong to the King Island Emu which has
>since become extinct.  Obviously, emus as a lineage are older than
>that.  however, the most recent book I have on the subject, a detailed
>monograph called "Ratites and Tinamous" by SJJF Davies (Oxford, 2002),
>casts doubt on any of the attempts to determine precisely how old these
>groups of birds are, and does not suggest a date.

There are much older fossils of the extant Dromaius novaehollandiae. Dating of Australian Pleistocene sites beyond the range of C14 is usually very uncertain, but at least some of the emu remains from the Cooper Creek area, e. g. Kudnampirra waterhole, date to the middle Pleistocene. Most extant avian species seem to have their origin in the Early Pleistocene or Pliocene, but there are very few sites with avian fossils from that time-range in Australia. Incidentally emu eggshell are rather common in Pleistocene and Holocene deposits in Australia, and quite useful for dating purposes.

Useful references:

Boles, W. E. 1992. Revision of Dromaius gidju Patterson and Rich, 1987, from Riversleigh, northwestern Queensland, Australia, with a reassessment of its generic position. In: Campbell, K. E., Jr. (ed.): Papers in Avian Paleontology honoring Pierce Brodkorb. Natural History Museum of Los Angeles County, Science Series, 36:195-208.

Boles, W. E. 1997. Hindlimb proportions and locomotion of Emuarius gidju (Patterson & R
ich 1987) (Aves Casuariidae) Memoirs of the Queensland Museum 41:235-240.

Boles, W. E. 2001. A new emu (Dromaiinae) from the Late Oligocene Etadunna Formation. Emu 101:317-321.

Patterson, C. & Rich, P. V. 1987. The fossil history of the emus, Dromaius (Aves: Dromaiinae). Records of the South Australian Museum 21:85-117.

Tommy Tyrberg