7 Jul 2015

When dinosaurs walked Golden Bay

9:25 pm on 7 July 2015

Some giant footfalls of history have returned to Nelson.

The story of New Zealand's only known dinosaur footprints, which were discovered in northwest Nelson in the mid 1990s, is part of a national touring exhibition that has just opened in Nelson.

Nelson Provincial Museum chief executive Peter Millward points out an artist's impression of the type of dinosaur that once strolled around northwest Nelson.

Nelson Provincial Museum chief executive Peter Millward points out an artist's impression of the type of dinosaur that once strolled around northwest Nelson. Photo: RNZ / Tracy Neal

It attracted almost 1000 viewers in its first few days, Nelson Provincial Museum chief executive Peter Millward said.

The exhibition is an outreach project by GNS Science and tells the story of the first discovery of dinosaur footprints in New Zealand.

The 70 million-year-old imprints in the sandstone and mudstone of Golden Bay were found by sedimentologist Dr Greg Browne - not by stumbling upon strange saucer shapes in the rocks but through a slow process of deduction.

Dr Browne, who is a scientist with GNS Science, said the discovery said as much about the science of the area as it did about dinosaurs and the history of life in New Zealand.

Nelson Provincial Museum chief executive Peter Millward checks out imprints of dinosaur footprints.

Mr Millward with imprints of the footprints Photo: RNZ / Tracy Neal

The area that is now northwest Nelson, which is made up of New Zealand's oldest rocks and landforms, tells the story of a close geological link with Australia.

Dr Browne said dinosaurs were among the fauna of the ancient supercontinent of Gondwana that became Antarctica, Australia and New Zealand.

"There used to be a great southern continent called Gondwana, or Gondwanaland, that existed in the Mesozoic Period, so we're talking 70 million years plus," Dr Browne said.

"It was a large continent that started to split up around about 100 million years ago and Zealandia began splitting away from the eastern seaboard of the Australian continent."

He said it was "just by chance really" that dinosaurs were living on the part that split away over millions of years to become New Zealand.

"Vegetation and animals that were part of the eco-system were transferred into an island."

Mr Millward explained that the rate of movement was about the same as the time it took fingernails to grow.

Footprints from the past

The dinosaurs that walked across the tidal flats of northwest Nelson in the late Cretaceous Age, which followed the Jurassic Period, left footprints that can be seen today.

The prints left by the toeless clawless sauropods range in size from five to 60 centimetres wide and up to 50 centimetres deep.

Sauropods, which had club-like feet, were the largest animals that ever lived in New Zealand, and were bigger than today's whales. The plant eaters were up to 40 metres long and weighed up to 100 tonnes. They were swimmers, which explained their coastal habitat.

The exhibition in Nelson has attracted throngs of excited school children, some of them fresh from having seen the latest dinosaur fright movie - Jurassic World. Connor McDonald, 12, was among them. He said he was fascinated by dinosaurs: "No one really knows about them."

The dinosaurs of New Zealand became extinct after the cataclysmic extraterrestrial event that destroyed much of life on earth, Dr Browne said.

"At the end of the Cretaceous Age, the big impact of a comet hitting the earth [in the area now known as the Yucatan Peninsula in Mexico] was felt around the world."

He said, by geological timeframes, New Zealand's dinosaurs became extinct in an instant.

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