New Zealand is part of the larger continent of Zealandia, which finished separating from the supercontinent Gondwana some 57 million years ago.

Some familiar animals were likely present in proto-New Zealand at this time, including our unique silent frogs, the ancient tuatara and many invertebrates. Tens of millions of years of dispersal of both plants and animals followed.

Moa are most closely related to the flying chicken-sized tinamous from South America, and kiwi are relatives of the giant extinct elephant birds from Madagascar. Indeed, Australia did not even exist as a discrete entity 50 to 60 million years ago; it was still firmly affixed to Antarctica and South America.

Exactly what routes the ancestors of moa and kiwi took to reach Zealandia remains unknown. They were part of a group of flying birds with a worldwide distribution called Lithornids, which lost flight many times independently and evolved into the ratites we know today.

The bones will speak

The St Bathans fossil deposit has given us an indispensable window into prehistoric New Zealand, and in many ways it is familiar – the bones of moa, kiwi, parrots, wrens and bats provide a reassuring continuity.

As the publication notes, though, there are also many strange things in the fossil deposit – crocodiles, a relative of flamingos and a giant turtle. There’s an Alice in Wonderland quality to St Bathans, and it’s a crucial piece of the story of Aotearoa New Zealand’s biological heritage.