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Flightless birds’ history upset by ancient DNA

Ancestors of kiwis and elephant birds didn’t just drift with the continents

5:56pm, May 22, 2014

RELATIVELY ODD  Ancient DNA has revealed an unusual pair of closest relatives: New Zealand’s flightless, roughly chicken-sized kiwi species (skeleton of adult Apteryx australis shown) and Madagascar’s huge elephant bird (egg of Aepyornis maximus shown). 

Madagascar’s elephant birds — which weighed as much as three or four people and went extinct several hundred years ago — turn out to be the closest known relatives of New Zealand’s chicken-sized kiwi.

This genealogical surprise is “a slap in the face” to a long-standing idea of how many flightless birds evolved, says evolutionary biologist Alan Cooper  of the University of Adelaide in Australia.  Realizing that continents moved around, biologists in the 1970s debated whether ostriches, kiwis and the rest of the flightless wonders called ratites arose when flightless common ancestors drifted apart by riding along on land masses that fragmented and separated.

In 1992 Cooper raised some doubts about the continent-riding idea when he and his colleagues extracted ancient DNA from bones of New Zealand’s hefty flightless moa, now extinct. As fellow travelers, moas and kiwis should have been close relatives. But they weren’t.

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