In soft sandstone on a New Zealand beach lie a series of very heavy footprints — the first evidence of dinosaur activity on the island.

The prints were probably made by large, plant-eating sauropods between 6 and 18 feet long, creatures that would have weighed several tons. The discovery was made by geologist Dr Greg Browne a decade ago. Browne made public his find only when he was certain of the dinosaur link, work that required several years of study.

The round markings, up to 2 feet across and 70 million years old, would have been made in beach sand and preserved by "wet sticky mud" washed in by the tide, though the exact site remains undisclosed to preserve the integrity of the find.

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In an interview with The New Zealand Herald, Browne describes his suprise at finding footprints in such an unusual location. "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."

Paleontologist Dr Hamish Campbell from New Zealand research organization GNS Science said scientists have yet to decide the best way to protect the prints.

"These are great features from a scientific point of view and because they relate to dinosaurs the public will be incredibly interested, he pointd out. "Somehow we've got to balance the interest of the public with privacy and conservation. Maybe one day there'll be a dinosaur park or reserve where people can see them," he said.

Read more at The New Zealand Herald,