The DNA secrets of what was our most common species of moa have been revealed in a new Harvard University study that one scientist says could be "game-changing".
The team used a new form of DNA sequencing, called high-throughput sequencing, to unravel the little bush moa's nuclear genome, or the make-up of a species' nuclear DNA.
Analysing mitochondrial DNA, which is passed down maternally, has enabled scientists to learn much about the evolution of species.
But downloading their nuclear DNA - the genetic building blocks responsible for determining or "coding" much more - has meant researchers could look even deeper.
In a study not yet peer-reviewed and published in a journal, experts from Harvard and Canada's Royal Ontario Museum used ancient DNA (aDNA) extracted from a single toe bone of a specimen of little bush moa.
The smallest and most widespread of the species, little bush moa once roamed forests across the North and South Islands before they, along with other moa, were hunted to extinction soon after the arrival of humans in the 13th century.
First retrieved by Kiwi paleozoologist Professor Trevor "Mr Moa" Worthy, the specimens had been held in collections of the Royal Ontario Museum.
Along with a near-complete mitochondrial genome, Dr Alison Cloutier and her colleagues recovered nearly 900 megabases of the moa nuclear genome, by mapping reads to a high quality reference genome for the emu.
The team were also able to isolate 40 repeating tracts of DNA, called polymorphic microsatellites, that could help scientists carry out population-level studies of moa in the future.
Among their key findings was that moa likely didn't become wingless due to gene loss, or pseudogenisation.
"This first nuclear genome assembly begins a new chapter in the already extensive history of moa aDNA research," the authors concluded.
Having the new moa nuclear genome would help studies of regulatory changes linked with flightless creatures, including ratites such as our kiwi.
Dr Nic Rawlence, a lecturer in ancient DNA at the University of Otago who has led studies rewriting the histories of some of our endemic species, said the new insights would prove important for our country.
"This will be a game-changing moment in our understanding of the evolution of New Zealand's unique fauna," Rawlence said.
"The sequencing of the first draft moa genome, for a long time a holy grail of sorts, will allow scientists to finally bring the power of the genomic revolution that has swept through science to answering some of the big questions regarding moa evolution and how they responded to New Zealand's dynamic geological and climatic history.
"Already, it looks the cause of moas' complete lack of wings may not be a simple case of gene loss, though further work is needed to determine why moa completely lack wings, compared to other flightless ratites."
The finding comes after a series of major revelations about the moa in recent years.
In 2014, it was revealed how the moa was more closely related to South America's tinamous than its old bushmate, the kiwi, and both moa and kiwi separately evolved to become flightless after their ancestors flew here.
It's been wildly proposed by Labour MP Trevor Mallard that moa could be revived, but scientists have pointed out the giant birds would make poor candidates for resurrection, and more recently-extinct species like the huia might be better options.
Worthy, based at Flinders University in Adelaide, said the moa genome illustrated "the huge problems faced by folk thinking they can resurrect an extinct species".
"Even if we had the entire genome, we would have no idea how to activate the genes, or which ones not to, nor what combinations of multiple genes one would need to have interact to create the animal," he said.
"The fact that the moa genome has most of the genes known for wings illustrates this point well."
There were multiple pathways and processes that interacted with such genes in their expression which could not be determined from the basic genome.
"Nevertheless, this genome will allow the study of evolutionary processes leading to moa, and perhaps at the basic level, help characterise the species of moa and their relationships rather better than has been possible using only a mitochondrial genome."