Lark Quarry dinosaur stampede

Introduction

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.)

Numerous 'fossil' dinosaur footprints or tracks are preserved there. This makes it a most important scientific discovery. It helps scientists to understand more about dinosaurs and their behaviour.

The trackways reveal an important chapter in the story of Australia's heritage, and in July 2004 the Dinosaur Stampede National Monument (Lark Quarry dinosaur trackways) was the second place to be included in the new National Heritage List. Its listing means that the trackways are protected under the Environment Protection and Biodiversity Conservation Act 1999 for future generations to enjoy.

• More about the National Heritage List

Lark Quarry countryside today.

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 and preserved.

In modern times, these have been uncovered by erosion, and then by the excavation of the site. Scientists can tell that a series of footprints were made by the same dinosaur as it walked or ran. This is known as a dinosaur 'trackway'.

The Flash entry page (248k) to this web site features an animated interpretation of the Lark Quarry stampede. Note that the smaller Ornithopod and Coelurosaur dinosaurs actually stampede towards the larger carnivorous Theropod dinosaur and not away from it as might be expected.

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.
 

Click here to see locations of dinosaur fossils discovered in Australia.

Flash (256k)

Area of trackways uncovered and protected by the Lark Quarry Conservation Building.

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.

Trackways clearly showing the path of the large Theropod.

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.

Scientists may also tell in which order the tracks were left. For example, later tracks would lie on top of earlier tracks.

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.

• Skartopus footprints - these were made by a herd of small Theropod dinosaurs called Coelurosaurs. They were carnivores, and might have eaten insects and small animals such as frogs and lizards.
  
  These Coelurosaurs walked and ran on their two hind legs. They left tracks about 4 to 5cm long and would have been about 20cm high at the hip, about the size of a modern chicken.
   
• Wintonopus footprints - a herd of somewhat larger Ornithopod dinosaurs left these footprints.
  
  The Ornithopod known from the Wintonopus footprints was a herbivore, eating low plants such as ferns and cycads that grew at that time. It also walked and ran on its hind legs. The tracks show that it grew up to between the size of a modern chicken and emu.
   
• Tyrannosauropus footprints - a single Theropod predator left a trackway of these footprints.
  
  This giant Theropod also walked and ran on its hind legs, leaving tracks over a half a metre long. It would have been about 8 or 9 metres long, about 2.5 metres high at the hip, and about 3.5 metres high at the head. It was a carnivore.

Lark Quarry dinosaur size comparison.

The trackways show Tyrannosauropus, Wintonopus and Skartopus footprints.

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 large predator (Theropod) approached from the north, with steps of up to 2 metres in length. The prints show it walked at about 8–9 km per hour. There are no running steps. Altogether eleven steps can be seen, but further steps are not preserved because past this point the rock has been eroded away.

After the first six steps the animal slowed down, and at the tenth step it began to turn to the right. This may have been in order to hunt a smaller animal such as a Coelurosaur or a Ornithopod.
 

Tyrannosauropus (large), Wintonopus (small) and Skartopus (very small) footprints.

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.

All of the stampeding dinosaurs ran in the same general direction, back from where the predator had come. This may have been so that they were not trapped against the edge of the water. Scientists know that the stampede happened after the big dinosaur approached because the tracks of the smaller dinosaurs overlie those of the Theropod. The Seymour Quarry, which is about 95 metres north east of Lark Quarry, shows more of the stampede tracks. At that point the fleeing dinosaurs were still running in the same direction.

Apart from recording the stampede, the tracks found at Lark Quarry show that small dinosaurs lived and travelled in quite large herds.

The excavation story

Discovery

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.

Excavation

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.

The quarry was named after Malcolm Lark, a volunteer who removed a lot of the overlying rock.

Conservation Building that protects the Lark Quarry trackways.

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 present Conservation Building that covers the trackways was constructed in 2002. This gives much better protection by

• controlling the temperature and the humidity
   
• preventing water running over the site after heavy rain
   
• keeping out dust and grit and
   
• preventing humans and animals from walking over the delicate site.

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.

Casts (copies) of sections of the dinosaur trackways can be seen at the Queensland Museum and at the South Australian Museum.