About 95 million years ago, a herd of two-legged dinosaurs, some as small as chickens and some about the size of emus came to drink at the muddy shore of a lake, located at what is now Lark Quarry, about 110 km southwest of Winton, in central-west Queensland, in Australia. Something caused them to panic, perhaps the presence of a large predator, and the herd swiftly swam across the lake. In doing so they left footprints on the soft mud which later got buried beneath sand and silt as the lake and river levels continued to rise and fall. Over thousands of millennia, the sandy bed, swamps and lush lowland forest dried up, and the sediment covering the footprints was compressed into solid rock.
Fifty years ago, a local station manager discovered the fossilized footprints while looking for opals. At first he thought they were fossilized bird tracks, but it wasn't until scientists visited the area in 1971 that the footprints began to reveal their true story. Today the footprints, referred to as the “dinosaur stampede” is preserved inside a building at Lark Quarry Conservation Park.
The site has about 3,300 separate footprints that seems to have been made by about 150 dinosaurs belonging to two different species - carnivorous coelurosaurs about the size of chickens, and slightly larger plant-eating ornithopods, some of them as large as emus. The area measures about 22 meters by 22 meters in size.
The herds of Coelurosaur and Ornithopod may have come down to a stream or lake to drink, when a large predator – a Theropod, appeared from the north causing the herd to flee across the lake. Later research however, challenge this story. Analysis of the sediments indicate that the area had no prehistoric lake. Instead, the deposits were made by an ancient channel of water flowing at different depths and speeds at different times. The researchers also didn’t find evidence of a coordinated run in one direction. Rather, the footprints were made over a period of time, perhaps several days, as dinosaurs crossed the channel at different times and under varying conditions. Based on track size and presumed skeletal proportions, the researchers estimated that the dinosaurs stood between five inches and five feet at the hips. And contrary to previous interpretations, only one species of dinosaur was responsible for the abundance of tracks.
We may never really know exactly what happened at Lark Quarry millions of years ago, but the site still represents one of the highest concentrations of dinosaur tracks in the world.
More locations where you can see dinosaur footprints:
- Cal Orcko, a 300 feet wall with over 5,000 dinosaur footprints
- Gantheaume Point in Broome
Sources: Dinosaurtrackways.com / Environment.gov.au / Wikipedia / NatGeo
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