Australia: The Land Where Time Began

A biography of the Australian continent 

Lark Quarry - A dinosaur stampede

Dinosaur Stampede National Monument 111 km SW of Winton

Lark Quarry Site, Winton, Queensland Lark Quarry site, Winton, Queensland

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.

Analytical protocols that incorporated 3-D structure were used to re-examine the largest dinosaurian tracks that have been found at Lark Quarry, central-western Queensland, Australia. The authors3 compared archival photos, replica specimens (about 1977) and the in situ tracks (2013) to account for changes to the surface of the tracks. During and after excavation damage to the tracks was evident, though in instances where there is a strong difference between the archival photographs and the replicas from the 1970s it is apparent the track morphology has been modified by the restoration.

Several of the track morphologies that were obtained from new 3D evaluation models show a considerable difference from the track outlines that were published in the original site description, even after accounting for damage and alteration that occurred recently. Some of the original outlines seem to represent simpler, stylised versions of the tracks, when compared with the new set of representations. They found that a number of the original outlines were more than 20 % larger than the in situ tracks, while cracks appear to have been incorporated as part of the margins of digital impressions. Overall, according to the authors the tracks that are best preserved show blunt digital impressions, which reaffirm the suggestion that the trackmaker was a large ornithopod and supporting a reassessment to cf. Iguanodontipus. The new analysis has also revealed the nature of the displacement rims associated with the tracks, and the overprinting of these rims by other ichnites – initially by tool marks, that the authors3  presume are by floating vegetation, and then by other dinosaurian tracks they suggest are assignable to Wintonopus latomorum. The authors3 say that in the context of these observations they can see no evidence of the Iguanodontipus trackmaker interacting with the W. latomorum trackmakers, which were smaller-bodied, because they say neither can be inferred to have been present at the tracksite at, or even close to the same time. The authors3 also say there is no evidence to support the suggestion that the movement of the W. latomorum trackmakers was triggered by the approach of the cf. Iguanodontipus trackmaker. They suggest the their study supports the idea that Lark Quarry is most likely to represent a complex time-averaged assemblages of multiple dinosaurian ichnites, which were preserved over an extended period of time, from hours to days, and it was bracketed by discrete phases of trackmaker activity as well as fluctuations in the depth of the water.

Conclusion

The subjective utilisation of track outlines, that are hand drawn, associated with the traditional approach to analysis of tracks, has the main limitation that the lack of reproducibility, which is particularly relevant to interpretation, understanding and monitoring of significant iconological data. According to Romilio & Salisbury researchers are limited in the usefulness that such outlines can provide for future potential research applications without representations that are accurate and objectively reproducible. Methods that are more objective, such as digital photogrammetry, have become available to iconologists, which are inexpensive and easy to use, which enable the documentation of 3D information of tracks as well as related structures.

The largest of the Lark Quarry tracks are indicated by the impressions of rounded digits and the lack of either a claw or digital pad impressions to be of ornithopodan in origin, and allows them to be reassigned to cf. Iguanodontipus. It is indicated by features of the track that the cf. Iguanodontipus trackmaker may have crossed the site at a time of subaerial exposure at a time when the soft sediments had high water content. Subaqueously formed tool marks that overprinted the displacement rims extend the time period between the formation of the large dinosaur tracks and at least some of the tracks formed by the much smaller dinosaurs assignable to W. latomorum. In this current study the authors3 found no evidence that was suggestive of both types of dinosaurian tracks b formed simultaneously or near simultaneously, and they find it hard to rationalise or substantiate any proposals for inferred interactions between the single large ornithopodan trackmaker and the other trackmakers at Lark Quarry.

 Conclusion

The subjective utilisation of track outlines, that are hand drawn, associated with the traditional approach to analysis of tracks, has the main limitation that the lack of reproducibility, which is particularly relevant to interpretation, understanding and monitoring of significant iconological data. According to Romilio & Salisbury researchers are limited in the usefulness that such outlines can provide for future potential research applications without representations that are accurate and objectively reproducible. Methods that are more objective, such as digital photogrammetry, have become available to iconologists, which are inexpensive and easy to use, which enable the documentation of 3D information of tracks as well as related structures.

The largest of the Lark Quarry tracks are indicated by the impressions of rounded digits and the lack of either a claw or digital pad impressions to be of ornithopodan in origin, and allows them to be reassigned to cf. Iguanodontipus. It is indicated by features of the track that the cf. Iguanodontipus trackmaker may have crossed the site at a time of subaerial exposure at a time when the soft sediments had high water content. Subaqueously formed tool marks that overprinted the displacement rims extend the time period between the formation of the large dinosaur tracks and at least some of the tracks formed by the much smaller dinosaurs assignable to W. latomorum. In this current study the authors3 found no evidence that was suggestive of both types of dinosaurian tracks b formed simultaneously or near simultaneously, and they find it hard to rationalise or substantiate any proposals for inferred interactions between the single large ornithopodan trackmaker and the other trackmakers at Lark Quarry.

Sources & Further reading

  1. Long, John A, 1998, Dinosaurs of Australia and New Zealand, University of New South Wales Press.
  2. 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.
  3. Romilio, A. and S. W. Salisbury (2014). "Large dinosaurian tracks from the Upper Cretaceous (Cenomanian–Turonian) portion of the Winton Formation, Lark Quarry, central-western Queensland, Australia: 3D photogrammetric analysis renders the ‘stampede trigger’ scenario unlikely." Cretaceous Research 51(0): 186-207. PDF

Links

  1. http://www.environment.gov.au/heritage/places/national/dinosaur-stampede/information.html
  2. Lark Quarry trackways
  3. Closet veggie-lovers?: 'Predatory' dinos ate plants

 

Author: M. H. Monroe
Email:
  admin@austhrutime.com
Last Updated 17/07/2014

 

Australian Dinosaurs
Archosauria
Burrowing Australian Dinosaur
Dinosaurs
Dinosaur Footprints
Fossil Sites
Iguanodontids
Muttaburrasaurus
Ornithischia
Reptiles
Saurischia
Triassic Australia
Jurassic Australia
Cretaceous Australia
Home
Journey Back Through Time
Geology
Biology
     Fauna
     Flora
Climate
Hydrology
Environment
Experience Australia
Aboriginal Australia
National Parks
Photo Galleries
Site Map
                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading