The kiwi can now be put alongside Phar Lap, Crowded House and Pavlova as Kiwiana classics Australians try to claim as their own.
Researchers at Flinders University in Adelaide have examined a 20-million-year-old fossil which they say shows the kiwi descended from an emu and had been able to fly here from Australia.
To make matters worse the research was lead by expatriate New Zealander Trevor Worthy.
Worthy discovered the fossil three years ago at St Bathans in Central Otago.
He said the study results were supported by genetic evidence that kiwi were related to the Australian emu and not the New Zealand moa, an enormous emu-like bird that became extinct some 700 years ago.
"One of the distinguishing attributes of the kiwi is that it lays an enormous egg, which is about a quarter of the bird's body weight and occupies most of the bird."
Research by the late evolutionary biologist Stephen Jay Gould which sought to explain the origins of the size of kiwi eggs, promoted the idea that kiwi were descended from a large moa-like ancestor, and had shrunk in size while retaining the egg size of this ancestor, Worthy said.
"This fossil from the early Miocene, about 20 million years ago, shows us that it's a tiny bird about one-third of the size of a small kiwi today,'' Worthy said.
"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."
DNA suggested the kiwi was closely related to the emu, meaning they shared a common ancestor that could fly, he said.
"It means they were little and volant [capable of flight] and that they flew to New Zealand."
Department of Conservation (DOC) bird expert Hugh Robertson said for more than a decade the established thinking was that the kiwi was closely related to the emu, but it did not mean it had flown here.
The kiwi could have been in New Zealand since the land split from Gondwanaland about 60 million years ago, he said.
The theory the kiwi got bigger over time was seen in other native birds in New Zealand, he said.
"The takahe has gotten larger over time and it's a pattern with Australian birds coming here."
The fossil find could be the first of its kind in this country, he said.
"As far as I know it's the first fossil recorded that dates back that far."
What will be the main motivation for humanity's future space endeavours?Related story: (See story)
The cost of losing nature