A new study done by researchers from University of Adelaide has suggested that emu is not the closest relative of kiwi birds as was previously thought.
The researchers added that the kiwi is most closely related to the extinct Madagascan elephant bird - a 2-3 metre tall, 275 kg giant.
The study added that both of these flightless birds were once able to fly.
The new study by the University of Adelaide's Australian Centre for Ancient DNA (ACAD) has succeeded in solving a 150-year-old evolutionary mystery about the origins of the giant flightless "ratite" birds, including emu and ostrich. These birds are found across the southern continents.
Some of the world's largest birds - such as the extinct giant moa of New Zealand and elephant birds of Madagascar - are also included in this group.
Kieren Mitchell, PhD candidate with ACAD, who performed the work, said that thje result was highly unexpected.
Mitchell added that New Zealand and Madagascar were only ever distantly physically joined via Antarctica and Australia, so the finding shows that ratite must have moved from one place to another by flying.
The findings are published in the journal Science.