Lark Quarry dinosaur stampede
Lark Quarry, 110km south of Winton in central Queensland,
is the site of the world's only known record of a
dinosaur stampede. (A 'stampede'
occurs when a herd of animals run in alarm or panic.)
How did dinosaur tracks form?
Dinosaurs would have come down to the lakes, waterholes
and streams to drink, and would have walked in the soft
mud. Usually these footprints would have been washed
away, but occasionally, as at Lark Quarry, they were
gently covered over with later deposits of sand or mud
Are there other dinosaur trackways?
Yes, dinosaur trackways have been found in other places.
One important discovery is on the north-west coast of
Western Australia, near Broome, where there are trackways
made by numerous dinosaurs. However, none of the other
discoveries show a dinosaur stampede, so the trackways
at Lark Quarry are unique.
How old are the Lark Quarry 'trackways'?
Scientists believe these tracks are of Mid Cretaceous Period (approximately 95 million years old), about the time Australia was separating from Antarctica. They are in a series of sedimentary layers called the Winton Formation.
How many dinosaurs made the tracks left at Lark Quarry?
The quarry has uncovered a large flat layer of mudstone containing the dinosaur tracks. The area is about 22 metres by 22 metres in size, and more or less triangular in shape. There are about 3300 separate footprints, and these seem to have been made by about 150 dinosaurs.
What can scientists tell from trackways?
The size of the footprints gives a very good idea of
the size of the dinosaur that made them. By comparing
the sizes and shapes of tracks with those made by known
kinds of dinosaurs in other places, scientists can form
a good idea of what the dinosaurs would have looked
like. These include, the depth of the prints that indicates
the weight of the animal, and the distance between the
footprints of the same animal, which shows whether it
was walking or running, and also how fast it was going.
What kinds of dinosaurs made the tracks at Lark Quarry?
There seem to have been three different species of dinosaur that left footprints at Lark Quarry.
What can scientists tell about the 'stampede'?
There were herds of Coelurosaur and Ornithopod present.
They may have come down to a stream or lake to drink.
The tracks show that there was then a stampede by the
herds of smaller dinosaurs (Ornithopod and Coelurosaur).
These herds comprised of about 150 dinosaurs. Scientists
believe that these dinosaurs were running, because the
distances between footprints is larger than the lengths
of the legs of the animals. The tracks indicate that
the Coelurosaurs ran at speeds of about 9-15 km per
hour, and the Ornithopods at about 10-30 km per hour.
The excavation story
The Lark Quarry site is about 110km south west of the western Queensland town of Winton. The footprints were first discovered in the 1960s by station manager Glen Seymour, in the nearby Seymour Quarry. He knew that the footprints were fossils, but thought that they must have been left by birds. He showed them to a local fossil expert Peter Knowles, who recognised them as dinosaur prints. He knew how important the find was, and showed it to fossil experts (Palaeontologists) from the Queensland Museum.
Palaeontologists from the Museum and the University
of Queensland excavated Lark Quarry during 1976–77.
Altogether they removed more than 60 tonnes of rock,
and uncovered about 210 square metres of the layer with
the fossils. This shows about 3300 dinosaur footprints.
Preserving the site
At first a sheltering roof was built over the site.
However, this did not totally stop the gradual damage
caused by being exposed to the weather.
The 374-hectare Lark Quary Conservation Park, of which
the trackways are a part, provides additional protection.
The park is looked after by the Queensland National
Parks and Wildlife Service, under the trusteeship of
the Queensland Museum and the Winton Shire Council.