Dinosaur footprints are New Zealand first
11 Nov 2009
Scientists have discovered 70 million-year-old dinosaur footprints in the South Island region of Nelson - the first evidence of the pre-historic monsters’ existence in New Zealand.
Geologist Greg Browne of the New Zealand government-owned research organisation, GNS Science, found the footprints while he was investigating rock and sediment formations in Whanganui inlet at Golden Bay.
The footprints were in six locations spread over an area of about 10km, and Dr Browne says the most plausible explanation is that they were made by sauropods.
NZ-first evidence
It is the first evidence of dinosaurs not only in the South Island but all of New Zealand, and Dr Browne says he’s carefully considered all possible geological and biological explanations for the features found in the rock.
One-by-one he ruled them out and, after comparisons with dinosaur footprints in similar-aged rocks in other parts of the world, he concluded the prints were made by sauropods - large herbivorous dinosaurs with long necks and tails and pillar-like legs.
Palaeontologist Dr Hamish Campbell of GNS Science said the find was "hugely exciting" and gave the scientists food for thought. "We will now go and examine rocks of comparable age," he said.
Unique preservation
Dr Browne said the footprints were made in beach sands and were probably quickly covered and preserved by mud from subsequent tides.
"What makes this discovery special is the unique preservation of the footprints in an environment where they could easily have been destroyed by waves, tides, or wind."
Up to 20 footprints were found at one location and the depressions are roughly circular, with the largest about 60cm in diameter. Most are smaller, typically between 10cm and 20cm in diameter, and were probably formed by dinosaurs between 2m and 6m in length and weighing several tonnes, said Dr Browne.
Zealandia
While palaeontologists know that dinosaurs were present in ancient New Zealand, which they refer to as Zealandia, the record of their presence is sketchy.
Dinosaur bones, mostly vertebrae, have been found at three locations, in northern Hawkes Bay, Port Waikato, and the Chatham Islands.
Dr Browne said the footprints added a considerable amount of information about how dinosaurs moved, how fast they moved and how big they were, as well as how soft the sediment was.
"This discovery opens the way for further study on a range of dinosaur-related issues in New Zealand."
Nelson submerged
Northwest Nelson was largely submerged under the sea between 70 and 20 million years ago and the footprints would have been covered by hundreds of metres of marine sediments, he said.
With the development of the modern plate boundary, New Zealand was uplifted and northwest Nelson emerged from the sea. During the past 20 million years, the overlying sedimentary rock has been eroded to expose the footprints.
Dr Browne's discovery will be published in the December issue of New Zealand Journal of Geology & Geophysics.
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