Lake Quarry

This park contains a trackway (Winton Formation) of early Late Cretaceous age that records a dinosaur stampede from about 95 million years ago. It seems a large carnivore attacked a group of smaller dinosaurs on what was then the shore of an inland sea. There are more than 3300 footprints and the number involved in the stampede has been estimated at 180 chicken-sized carnivorous theropod Coelurosaurs (Skartopus) and Wintonopus, a bantam to emu-sized herbivorous ornithopods. These tracks are among the best preserved dinosaur trackways in the world, hence it is possible to gain more information from them than from a less well preserved site. The identity of the the 3 species is not known, but they belong to 3 footprint taxa. A footprint taxon is allocated to an animal that makes a recognised footprint, though the species of animal responsible it not known. It is not certain that all individuals of a given footprint taxon are the same species, but it allows the sorting of the animals into rough categories.

The scene, as reconstructed, of that occasion was a mixed herd of 2 small dinosaur footprint taxa, chicken-sized theropods known as Coelurosaurs (Skartopus) and Bantam to emu-sized herbivorous ornithopods (Wintonopus) were trapped against a cliff by a large carnivorous theropod dinosaur of footprint taxon Tyrannosauropus, which is thought to have been about 12 m long because its footprints were 75 cm in length. The only escape path for the trapped animals was past the carnivore, which they took at high speed. It has been estimated that the whole drama was played out in about 10 seconds, with some of the herbivore tracks indicating they were travelling at about 20 km/hr. It hasn't been determined if they all escaped. The footprints were made on a mudflat that was covered by water soon after the event and filled with sediment while they were still fresh.

The flocking behaviour found at this site was the basis for the scenes of flocking behaviour included in the movie Jurassic Park and the documentary series Walking with Dinosaurs.

What was a 'flock' of theropod Coelurosaurs (Skartopus) and Wintonopus doing in what appeared to be a mixed herd of herbivores at the water's edge may be explained by a recent study that found evidence that suggests many Coelurosaurs, always assumed to be predators, may actually have been herbivores. See link 3.

Track reassessment² - a case of mistaken identity

Tracks of the alleged theropod Tyranosauropus were subjected to multivariate analysis, a method used to differentiate between ichnites (fossilised footprints) of theropod and ornithopod dinosaurs. The authors suggest the footprint may have actually been made by the ichnotaxon Amblydactylus gethingi an iguanodontian ornithopod. This non-hadrosaurid styracosterman, and considering the age and geography of Lark Quarry the the maker of the track may have been similar to Muttaburrasaurus Langdoni.

Sources & Further reading

Long, John A, 1998, Dinosaurs of Australia and New Zealand, University of New South Wales Press.
Romilio, Anthony, and Steven W. Salisbury. "A Reassessment of Large Theropod Dinosaur Tracks from the Mid-Cretaceous (Late Albian–Cenomanian) Winton Formation of Lark Quarry, Central-Western Queensland, Australia: A Case for Mistaken Identity." Cretaceous Research 32, no. 2 (4// 2011): 135-42.

Links