A recent study now suggests that the tracks may have been made by swimming and wading dinosaurs, rather than running dinosaurs.
University of Queensland palaeontologist Anthony Romilio, who led the study on the 95 to 98 million year old tracks, said they were preserved in river sediments when the area was part of an expansive 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,” Romilio 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 this was the case, we would expect to see a much flatter impression of the foot preserved in the sediment.”
The study, published in the Journal of Vertebrate Palaeontology, found that the river in question might have been a preferred travel route for the herbivorous bipedal dinosaurs, which ranged in size from emu to chicken-sized animals.
Lark Quarry is one of the most complex dinosaur track sites in the world, with a very high number of footprints.
Previous research at the site identified, among others, the tracks of two types of smaller dinosaur: the long-toed tracks of Skartopus australis, and the shorter-toed impressions of Wintopus latomorum.
However, 3D analysis has allowed for a newer understanding of the larger sequence of tracks at the site. “The 3D profiles of Skartopus tracks reveal that they were made by a short-toed [dinosaur] dragging its toes through the sediment, thereby elongating the tracks,” Romilio explained.
Previous research by Romilio and his supervisor Dr Steve Salisbury also suggested that the larger tracks were made by an herbivorous dinosaur rather than a large carnivorous theropod, as previously thought.
“Taken together, these findings strongly suggest Lark Quarry does not represent a ?dinosaur stampede?,” Romilio concluded.
Salisbury said that regardless of how it is interpreted, the new findings take nothing away from the importance of the site.
?Lark Quarry is, and will always remain, one of Australia?s most important dinosaur track sites,” he said.
The high density of the 4000 tracks exposed at the site, combined with the range of variation that they exhibit, make Lark Quarry one of the most important dinosaur track sites in Australia.
Source: Australian Geographic