Polar dinosaur trackways found in Victoria

Australian Geographic: Polar dinosaur trackways found in Victoria
EACH AROUND THE SIZE of a human handprint, several dozen steps recorded in the sand 100 million years ago make up the largest collection of the dinosaur footprints ever found In Victoria. Discovered in two sandstone blocks at Melanesia Beach near Cape Otway, this is only the fourth time dinosaur footprints have been found in the state.

One block is of particular interest, as it contains the first known dinosaur trackway (sequence of steps) ever found in Victoria: three footprints made by a small carnivorous dinosaur about 105 million years ago during the Early Cretaceous period.

"This is the most significant dinosaur track discovery in Victoria," says Dr Tom Rich, a palaeontologist at Museum Victoria in Melbourne, and co-author of a paper detailing the find. "There are at least 24 dinosaur tracks [here], made by a variety of dinosaurs."

Creating a good impression

"What is significant about dinosaur footprints - as opposed to dinosaur bones or teeth - is the evidence of the presence of dinosaurs," says Tom. "The trace fossils tell us how the dinosaurs were living in the area at the time."

"Fossil footprints in Australia are quite rare and can reveal new information about the types of dinosaurs there were in the area," adds Dr Aaron Camens, a marsupial trackways expert at the University of Adelaide. "Well preserved prints can tell us what the fleshed foot of the animal looked like. They can be used to examine how the animal walked, and trackways can even yield information about speed, movement and behaviour."

Tom and his coworkers believe the footprints were made by ornithomimosaurs or 'bird-mimic' dinosaurs that ranged in size from a rooster to a cassowary. "We can estimate the speed - somewhere between 7 and 9 km/h - based on the spacing of the tracks and the size of the tracks," says Tom. "We also can estimate the height of the animal, probably about four times the maximum length of the tracks."

The prints were left by animals that were likely to have been different ages and were walking over swampy ground created as snow melted across floodplains in the spring. At this time Victoria would have been within the Antarctic Circle, and would have been cold and completely dark for much of the year.

"These prints differ from others found in the region as they are made by [carnivorous] theropod dinosaurs instead of [herbivorous] ornithopods," says Dr Steve Salisbury, a palaeontologist at the University of Queensland who was not involved in the research. "It's hard to put these footprints into context. It may be that the prints were made at a similar time, but even that's hard to confirm, given how they were found on the beach."

Get in on the act
One of the sandstone slabs was first spotted by local landowner Greg Denney. Professor Pat Vickers-Rich a palaeontologist at Monash University and co-author of the paper describes Greg as "one of the world's best dino trackers."

Both Pat and Steve encourage interested members of the public to look for these types of fossils. "If footprints have already been found in a certain spot, that's always a good place to look for more," Steve says. "But in a lot of cases it can be hard for the untrained eye to tell if a footprint is dinosaurian."

The key is to have any potential find verified but leave it undisturbed, Steve says. "Taking photos is a great way to find out if you have something of interest, but unless you know the law for the area you are in, it is always best not to disturb a new find. I was just in the Kimberley, where there are many footprints and tracksites that are very important to the local aboriginal culture." he says. "To take any of those fossils would be a serious offence."

The discovery was published this week in Alcheringa: An Australasian Journal of Palaeontology.