Queensland paleontologists have discovered the world's only recorded dinosaur stampede is largely made up of the tracks of swimming, not running, animals.
A University of Queensland PhD candidate, Anthony Romilio, led the study of thousands of small dinosaur tracks at Lark Quarry Conservation Park in Queensland's central west.
The tracks, which are 95 million to 98 million years old, are preserved in beds of siltstone and sandstone deposited in a shallow river when the area was part of a vast, forested floodplain.
''Many of the tracks are nothing more than elongated grooves, and probably formed when the claws of swimming dinosaurs scratched the river bottom,'' Mr Romilio said on Wednesday.
''Some of the more unusual tracks include 'tippy-toe' traces - this is where fully buoyed dinosaurs made deep, near vertical scratch marks with their toes as they propelled themselves through the water.
''It's difficult to see how tracks such as these could have been made by running or walking animals. If that was the case we would expect to see a much flatter impression of the foot.''
Mr Romilio said the swimming dinosaur tracks at Lark Quarry belonged to small, two-legged herbivorous dinosaurs known as ornithopods.
Previous research had identified two types of small dinosaur tracks at Lark Quarry: long-toed tracks, called Skartopus, and short-toed tracks, called Wintonopus.
The new research about the nature of the Lark Quarry tracks was published in this month's Journal of Vertebrate Paleontology.