The group includes kiwi, moa, emu, cassowaries, ostriches, tinamous and rheas. Nearly all the ratites live in the Southern Hemisphere - and we believe their original home was Gondwanaland, the ancient super-continent that once included South America, Africa and Madagascar, Antarctica, Australia, New Zealand and the Indian subcontinent

Most ratites are flightless because their breastbone (sternum) is flat – there is no keel to attach the strong muscles needed for flight.  One ratite can fly – the South American tinamous.  

Their flat chest gave ratites their name. Ratis means "raft" in Latin - a boat without a keel.

Ratites can best be distinguished by their mouth.   All ratites, living and extinct, share the same arrangement of bones in the roof of their mouth, evidence they shared a common ancestor. Some scientists prefer the name "palaeognath" to describe ratites because it means "old mouth".

The Smallest Ratite

The ratite group contains some of the world’s largest birds, including emu, ostrich and rhea.  Kiwi are the smallest ratite.  When it was first described in 1813, a sceptical audience thought it was a hoax and demanded to see a specimen of this strange, nocturnal, burrowing bird.

How Ratites Evolved

Ratite species evolved from a common ancestor. In Africa they turned into ostriches, in South America rheas and tinamous, and in Madagascar, the enormous (but extinct) elephant bird.

Scientists once believed that here in New Zealand, ratite ancestors evolved into two separate birds - moa (now also extinct) and kiwi.  But that story changed recently.

By studying the DNA of different ratites, and looking at the tiny details of modern ratites' bodies, scientists believe the kiwi is more like the Australian emu and cassowary than it is like the moa. What the researchers think this means is that only the moa ancestor was aboard when New Zealand broke away from Gondwanaland 80 million years ago. Kiwi, ostrich, emu and cassowary ancestors developed outside New Zealand, and the kiwi migrated here later.