Dinosaur markings may indicate a river crossing: study
QUEENSLAND paleontologists have discovered stampeding dinosaurs in central-west Queensland were most likely swimming rather than running.
The 95-98 million-year-old tracks in the Lark Quarry Conservation Park show claw scratches and "tippy-toe" grooves mark the world's only recorded dinosaur stampede.
University of Queensland PhD candidate Anthony Romilio led the study of thousands of small dinosaur tracks preserved in thin beds of siltstone and sandstone deposited in a shallow river when the area was part of a vast, forested floodplain.
He said, together with other findings, the tracks might now indicate a river crossing rather than a stampede.
"Many of the tracks are nothing more than elongated grooves, and probably formed when the claws of swimming dinosaurs scratched the river bottom," he said.
"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 preserved in the sediment."
Mr Romilio said that similar looking swim traces made by different sized dinosaurs also indicated fluctuations in the depth of the water.
"The smallest swim traces indicate a minimum water depth of about 14cm, while much larger ones indicate depths of more than 40 cm," Mr Romilio said.
"Unless the water level fluctuated, it's hard to envisage how the different sized swim traces could have been preserved on the one surface.
"Some of the larger tracks are much more consistent with walking animals, and we suspect these dinosaurs were wading through the shallow water."
Mr Romilio said the swimming dinosaur tracks at Lark Quarry belonged to small, two-legged herbivorous dinosaurs known as ornithopods.
