The wonderful lizards of Oz: Over 20 three-toed dinosaur tracks found on Australian coast



A group of more than 20 three-toed dinosaur tracks has been discovered on the coast of Victoria, Australia.



The find is the largest and best collection of polar dinosaur tracks ever found in the Southern Hemisphere.

It offers a rare glimpse into animal behaviour during the last period of pronounced global warming, about 105million years ago.

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Sunken treasure: A group of more than 20 three-toed dinosaur tracks has been discovered on the coast of Victoria, Australia. The find is the largest and best collection of polar dinosaur tracks ever found in the Southern Hemisphere

Lead researcher Anthony Martin, from Emory University in Atlanta, Georgia, said: 'These tracks provide us with a direct indicator of how these dinosaurs were interacting with the polar ecosystems, during an important time in geological history.'

The three-toed tracks are preserved on two sandstone blocks from the Early Cretaceous Period.



They appear to belong to three different sizes of small theropods - a group of bipedal, mostly carnivorous dinosaurs whose descendants include modern birds - and were found on the rocky shoreline of remote Milanesia Beach, in Otways National Park.

This area, west of Melbourne, is known for energetic surf and rugged coastal cliffs, consisting of layers of sediment accumulated over millions of years.

Riddled with fractures and pounded by waves and wind, the cliffs occasionally shed large chunks of rock, such as those containing the dinosaur tracks.

One sandstone block has about 15 tracks, including three consecutive footprints made by the smallest of the theropods, estimated to be the size of a chicken.

Dr Martin spotted this first known dinosaur track-way of Victoria in June last year. He was on the lookout, since he had earlier noticed ripple marks and trace fossils of what looked like insect burrows in piles of fallen rock.

He said: 'The ripples and burrows indicate a floodplain, which is the most likely area to find polar dinosaur tracks.'

Lead researcher Anthony Martin sits in front of two tracks. The three-toed imprints are preserved on two sandstone blocks from the Early Cretaceous Period

The second block containing tracks was spotted about three hours later by Greg Denney, a local volunteer who accompanied Dr Martin and Thomas Rich, from the Museum of Victoria, on that day's expedition.

That block had similar characteristics to the first one, and included eight tracks. The tracks show what appear to be theropods ranging in size from a chicken to a large crane.

Dr Martin said: 'We believe that the two blocks were from the same rock layer, and the same surface, that the dinosaurs were walking on.'

The small, medium and large tracks may have been made by three different species, he said.



'They could also belong to two genders and a juvenile of one species – a little dinosaur family – but that's purely speculative.'

The Victoria Coast marks the seam where Australia was once joined to Antarctica.

During that era, about 115 to 105million years ago, the dinosaurs roamed in prolonged polar darkness.

The Earth's average temperature was 68F - just ten degrees warmer than today - and the spring thaws would cause torrential flooding in the river valleys.

The tracks were found on the rocky shoreline of remote Milanesia Beach, in Otways National Park. They appear to belong to three different sizes of small theropods - a group of bipedal, mostly carnivorous dinosaurs whose descendants include modern birds

The dinosaur tracks were probably made during the summer, Dr Martin said.

'The ground would have been frozen in the winter, and in order for the waters to subside so that animals could walk across the floodplain, it would have to be later in the season,' he explained.

Lower Cretaceous strata of Victoria have yielded the best-documented assemblage of polar dinosaur bones in the world. Few dinosaur tracks, however, have been found.

In February 2006, Dr Martin found the first known carnivorous dinosaur track in Victoria, at a coastal site known as Dinosaur Dreaming.

In May 2006, during a hike to another remote site near Milanesia Beach, he discovered the first trace fossil of a dinosaur burrow in Australia.

That find came on the heels of Martin's co-discovery of the first known dinosaur burrow and burrowing dinosaur, in Montana.

The two discoveries suggest that burrowing behaviours were shared by dinosaurs of different species, in different hemispheres, and spanned millions of years during the Cretaceous Period.