Bad luck, New Zealanders: the kiwi may be descended from a flying Aussie.
Two fossils about 16 to 19 million years old found in Central Otago from the same genus as the kiwi suggest it might have descended from the same ancestor as the emu, a study has found.
The fossils are of a tiny bird about a third of the size of a small kiwi which could possibly fly, suggesting it may have flown from Australia.
Dr Paul Scofield of Canterbury Museum, who took part in the study along with scientists from Te Papa museum and Flinders University in Adelaide, says this suggests an alternative to earlier theories based on the large size of kiwi eggs.
That theory suggested the kiwi evolved from the giant moa, with the bird shrinking in size while the egg size remained.
"It suggests the opposite is, in fact, the case - that the kiwi has developed towards a larger size, a trend that is seen in many birds from the early Miocene," he said.
The study backs up earlier analysis of molecular data which had already shown the kiwi was more closely related to the emu than the moa.
"And if, as the DNA suggests, the kiwi is related to the emu, then both shared a common ancestor that could fly. It means they were little and had wings, and that they flew to New Zealand," Dr Scofield said.
The fact that New Zealand is now thought to have separated from East Gondwana later than originally believed - about 55 million years ago - makes it easier to imagine the bird making it across the much shorter Tasman Sea of those times, the research paper says.
Dr Scofield said researchers would need to find wing bones to put the theory beyond all doubt.
