The kiwi bird’s DNA has been found to be linked not to the emu but to the elephant bird.
The elephant bird hailed from Madagascar and stood two to three meters in height. It had a weight of 275 kilograms. And believe it or not but a long time ago both of these birds were able to fly with relative ease.
A new study was conducted by by the University of Adelaide's Australian Centre for Ancient DNA (ACAD), has resolved the 150-years old mystery of the giant birds such as the ostrich and emu that could not fly. The issue concerned the giant moa bird and the elephant bird both of which were extinct.
These land-bound birds were known as the ratite species. DNA was isolated from the bones of two elephant birds and it matched the DNA of the kiwi. The evidence is mind-boggling since Madagascar and New Zealand were not even remotely joined together in ancient prehistoric times.
"This result was about as unexpected as you could get," says Mr Kieren Mitchell, PhD candidate with ACAD, who performed the work. "New Zealand and Madagascar were only ever distantly physically joined via Antarctica and Australia, so this result shows the ratites must have dispersed around the world by flight."
The only hypothesis that makes sense is that these birds must have had the power of flight long ago. That was how they got disseminated as a species from here to there.
"It's great to finally set the record straight, as New Zealanders were shocked and dismayed to find that the national bird appeared to be an Australian immigrant," says Professor Cooper. "I can only apologise it has taken so long!"
The ratite birds seem to have appeared midway on the time scale between the dinosaurs and the mammals. Of course, these large birds were heavy plant eaters but when the mammals gained dominance, they couldn’t compete as far as the food supply was concerned. The research team were able to use the elephant bird DNA to estimate when the ratite species had separated from each other.
"The evidence suggests flying ratite ancestors dispersed around the world right after the dinosaurs went extinct, before the mammals dramatically increased in size and became the dominant group," says Professor Cooper.
"We think the ratites exploited that narrow window of opportunity to become large herbivores, but once mammals also got large, about 50 million years ago, no other bird could try that idea again unless they were on a mammal free island – like the Dodo."
The ratites had a complex evolution. Their bodies ultimately began shrinking and soon they were left as flightless although powerful birds in their own right.
"We can now see why the evolutionary history of the ratites has been such a difficult problem," says co-author Professor Mike Lee, of the South Australian Museum and University of Adelaide. "Many of them independently converged on very similar body plans, complicating analysis of their history."
Fossils of kiwis found recently point in the direction of their being able to fly not too long ago. The clues have all merged after a lot of brainstorming and creative craziness. It seems that what is obvious in the beginning may have more complicated explanations deep beneath the surface.
"We recently found fossils of small kiwi ancestors, which we suggested might have had the power of flight not too long ago," says co-author Flinders University's Dr Trevor Worthy. "The genetic results back up this interpretation, and confirm that kiwis were flying when they arrived in New Zealand."
"It also explains why the kiwi remained small. By the time it arrived in New Zealand, the large herbivore role was already taken by the moa, forcing the kiwi to stay small, and become insectivorous and nocturnal."
Alan Tennyson, Curator of Vertebrates at Te Papa, New Zealand's national museum, says: "The New Zealand kiwi is an integral part of this country's culture and heritage. It's fitting that Te Papa's scientific collections have been used to resolve the mystery of its origins."