Frogs have been making a leap of faith for millions of years. It turns out they knew how to jump long before they knew how to land.

And Kiwi researchers have been at the forefront of unlocking one of nature's evolutionary mysteries.

Otago University scientists observed a primitive New Zealand species, the Leiopelmatidae, flop over and over again, and compared the landings to a more highly-evolved species.

The more developed frogs flex their legs mid-leap, setting themselves up for a perfect landing on their feet.

The scientists found that this shift to "early hindlimb recovery" was a key feature in the animals' evolution.

It showed that frogs had an ability to leap quickly into the water, rather than to move around on land.

Otago University's Phil Bishop filmed three primitive frog colonies in New Zealand using slow-motion and sent the footage to fellow researchers in the United States.

Belly-flopping means the frogs cannot jump again quickly, which challenges the theory of why frogs learned to jump in the first place.

The study has been published in several international science journals.