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No dinosaur stampede at Lark Quarry – so what really happened?

Everyone loves a good dinosaur story and they don’t come much better than the dramatic dinosaur stampede found in Queensland’s outback. But did a stampede really happen? In the late 1970s at Lark Quarry…

Dinosaur footprints at the Lark Quarry site. Steven Salisbury

Everyone loves a good dinosaur story and they don’t come much better than the dramatic dinosaur stampede found in Queensland’s outback. But did a stampede really happen?

In the late 1970s at Lark Quarry, about 110km southwest of Winton, central-west Queensland, half a hillside was removed to reveal a surface of rock pitted with thousands of three-toed dinosaur tracks.

There was a series of large tracks heading off to the southwest and thousands of smaller ones, most of which are directed to the northwest.

The original interpretation that was published in 1984 proposed that the set of large tracks were made a large-bodied carnivorous theropod dinosaur, perhaps something akin to the mighty Tyrannosaurus. The smaller tracks were thought to belong to small-bodied coelurosaurian theropods and herbivorous ornithopods.

It was estimated that there were more than 150 of the smaller dinosaurs. Given that nearly all their tracks are aligned in the same direction, and that some of them were imprinted into the larger tracks, it was proposed there must have been a stampede, most likely triggered by the approach of the large meat-eating theropod.

The stampede theory makes for a good story. But did it really happen that way?

Stampede story a popular attraction

This is a great story, and it definitely helped bring Lark Quarry to life. Stephen Spielberg liked it so much it became the inspiration behind one of the scenes in his 1993 film Jurassic Park.

Tourists love it as well, with many going out of their way to visit Lark Quarry and have the story told to them by professional guides.

The state and federal governments liked it too. Approximately $A3.2 million was put into the construction of purpose-built building to protect the site, and in 2004 it was given National Heritage Listing and renamed the Dinosaur Stampede National Monument.

But did a dinosaur stampede really happen at Lark Quarry?

The greatest story ever told … was just a story

Around 2010, we began to look more closely the large Lark Quarry dinosaur tracks. When various proportions of the outlines that had been published in 1984 were compared alongside other dinosaur tracks, they appeared to belong to a plant-eating ornithopod rather than a theropod.

Anthony Romilio re-examines the footprints at Lark Quarry. Steven Salisbury

Could it be that the large Lark Quarry trackmaker wasn’t a theropod?

If it was a large-bodied ornithopod, maybe something similar to Muttaburrasaurus, which we know inhabited this part of Queensland around the time the Lark Quarry tracks were made, would its approach have caused the smaller dinosaurs to stampede?

Artistic rendering of the large Lark Quarry track-maker: a bipedal ornithopodan dinosaur, similar to but smaller than Muttaburrasaurus langdoni. Anthony Romilio

When we published our results in 2011, many of our colleagues thought it was great; they’d also had doubts about the identity of the large track-maker.

A stampede of dispute

But others were aghast. Chief among these was Dr Tony Thulborn, formerly at the University of Queensland and lead author on the original 1984 publication in which the tracks had been described, and the stampede scenario first proposed.

In a response that came out in 2013, he labelled our claims as “iconoclastic”. He considered the methods we had used to analyse the track outlines to be flawed, and that in obtaining our results we had in some way “fabricated” our data.

His main gripe seemed to be that we had altered the outlines of some of the tracks to suit the analytical method we chose to employ.

Analysing the footprints in 3D. Anthony Romilio

The analytical method we used required the use of complete track outlines. The outlines that had been published in 1984 had dotted portions to them where a definite outline was presumably hard to make out.

There were different versions of some outlines, and the dotted parts weren’t always in the same place. In subsequent publications by Thulborn and others, some of the track outlines had been filled with colour, while others had the dotted parts joined. After convincing ourselves that the 1984 outlines were good approximations of the tracks, we decided to join the dots.

What the ensuing controversy highlighted was just how problematic the construction of track outlines can be. The majority of dinosaur tracks are 3D structures, and any representation of them in 2D means that information relating to depth is lost or compressed.

Creating an outline therefore depends on how the investigator interprets the track, making them highly subjective. This was clearly the case with the large Lark Quarry tracks. Where some saw dots or clear, unbroken lines, others saw red.

Using digital photogrammetry, we were able to approach the problem in a far more objective way.

This technique involves taking a series of photographs and then stitching them together to create a 3D model. The results can easily be reproduced, and none of the 3D information relating to track depth is lost. If you consider an outline, it’s simply a matter of selecting a contour line around or within part of the track.

Tracks in time: A – One of the large Lark Quarry tracks as it appeared after excavation c. 1977; B – 3D digital relief from new study; C – outline of 3D relief from new study; D – outline published in 1984. A - Queensland Museum; B & C - Romilio and Salisbury (2014); D - Romilio and Salisbury (2014), adapted from Thulborn and Wade (1984)

The 3D photogrammetric analysis of the large tracks that we published this year in Cretaceous Research shows them to be very different to how they were first portrayed in 1984. The dinosaur that made these tracks had broad feet with flat, rounded toes.

There is no evidence of separate pads beneath the toes or the heel, and there is no evidence of sharp claw impressions; characteristics that would normally be expected had they been made by a theropod.

Overall, they are a good match for tracks from Europe and Asia that are thought to have been made by large-bodied iguanodontian ornithopods, animals similar to Muttaburrasaurus.

Something else revealed in the images

The 3D images also showed something else. Most of the large tracks have raised margins around them. These “displacement rims” typically occur when the ground in which a track is made is saturated, but not covered in water.

This suggests that the large Lark Quarry track-maker walked across the site when the surface was wet, but probably not underwater.

3D relief of one of the Lark Quarry ornithopod footprints, with arrows showing the position of drag marks incising the side of the footprint’s pressure bulge. Anthony Romilio

The displacement rims around some of the large tracks are disrupted by drag marks, probably caused by partially floating vegetation. These could only have been made when water covered the site some time after the large dinosaur traversed it.

Since both the large footprints and drag marks have small dinosaur tracks overprinting them, the dinosaurs that made the smaller tracks must have crossed the area much later. From research that we published in 2013 we also know that some of these smaller dinosaurs were running, some were wading and some were even swimming.

No evidence of a stampede

The timing between the formation of the larger tracks, the vegetation drag marks and the smaller tracks could be anywhere from hours to days.

The sequence of track-forming events at Lark Quarry as inferred in the new study. 1 - Progression of the large-bodied ornithopod during likely subaerial track surface conditions; 2 - the formation of drag marks by partially buoyed vegetation; 3 - the progression of at least some of the small-bodied ornithopod track-makers, some of which were swimming. Anthony Romilio

The most likely scenario that could account for the series of events that produced Lark Quarry is probably a gentle rise and fall in the water level of a river that flowed through the area approximately 93 million years ago.

During this time various dinosaurs and a few floating bits of vegetation crossed the site. Some point after all the tracks were formed the entire surface was probably exposed and allowed to harden, with another rise in water eventually burying it in layer of sand before any features in it weathered away.

We may never really know exactly what happened at Lark Quarry all those millions of years ago. But we can present interpretations of what we think happened based on the evidence at hand.

In the case of Lark Quarry, the evidence is written in stone. As scientists, we just need to learn how to read it, and the way we read the evidence can change as science progresses. If new techniques allow us to refine the way we see things, then our interpretations will likely change. That’s science.

What the scientific community and the public at large make of our reading of the evidence is something we can’t always control. But at some point, the dust, or in this case, mud, will eventually settle.

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10 Comments sorted by

  1. Iain Davidson

    Archaeologist

    So the question is: will the public stampede to Lark Quarry to see the new interpretation? It is not a flippant question. I have no doubt that the motivation for spending large amounts of money on the preservation of the site so that it can be seen by the public (including me and my sons about 13 years ago) was that it would attract tourists who would like the "good story" of conflict all those years ago. Without the conflict, the story is not so sexy (better, but not so sexy, like so many of us). This is the problem with all heritage preservation as tourist attractions--there has to be a consideration of what the interpreters think the audience will want. There is, of course, a further irony. If I am right that the new interpretation would not have attracted the interest that led to the preservation, getting it right in the first place might not have allowed a re-interpretation.

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    1. David Hudson

      nature refuge manager at Natural Resource Management

      In reply to Iain Davidson

      I had the unforgettable experience of visiting the site 15 or so years back, before the flash interp centre was built. While it was the story that attracted me it became irrelevant. I drove out late in the afternoon. I was the only one around as the sun was setting. The ancient landscape, the silence and the history embedded in that rock just evoked the most amazing feelings of being thrown back millions of years. The hairs on my neck still rise just thinking about it. So I think the setting could provide as much of an attraction as the story, if done right.

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    2. Steven W. Salisbury

      PhD; Senior Lecturer, School of Biological Sciences at University of Queensland

      In reply to David Hudson

      Hi Iain, David,

      In response to Iain’s comment, I have to agree with David. The new interpretation should take nothing away from the beauty of the site, its scientific significance or its heritage value. It still contains one of the highest concentrations of dinosaur tracks anywhere in the world. As we argued in our 2013 paper, many of the smaller tracks appear to be swim traces, and in that context Lark Quarry is the only place in Australia where these types of tracks are preserved. In terms…

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    3. Iain Davidson

      Archaeologist

      In reply to Steven W. Salisbury

      I agree with David and Steven. The question is whether the site would have been preserved without the dramatic story.

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  2. Regina Magierowski

    Ecologist

    To prove/disprove that the tracks were formed by a stampede shouldn’t the authors describe their interpretation of the numerous small tracks and not the ones formed by a single large dinosaur?

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    1. Steven W. Salisbury

      PhD; Senior Lecturer, School of Biological Sciences at University of Queensland

      In reply to Regina Magierowski

      Hi Regina,

      Thanks for your comment. We did indeed focus on the nature of the small tracks that comprise the ‘stampede’ in a paper that came out last year. There is a link to that paper in the article, but if you missed it, here it is:

      Romilio, A., Tucker, R.T. and Salisbury, S.W. 2013. Re-evaluation of the Lark Quarry dinosaur tracksite (late Albian–Cenomanian Winton Formation, central-western Queensland, Australia): no longer a stampede? Journal of Vertebrate Paleontology 33(1), 102–120.

      You…

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  3. Andrew Simpson

    Honorary Fellow, Department of Ancient History at Macquarie University

    Good to see the "non-stampede" interpretation of Lark Quarry get some exposure. Many have questioned the original interpretation. Whether the "stampede" story assisted it's preservation as a special piece of natural heritage is an interesting question. I'd like to think that the rarity of the site is reason enough for preservation and public interpretation regardless.

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  4. Stephen Poropat

    Palaeontologist

    As with the earlier papers written on this subject led by Anthony (Romilio and Salisbury, 2011; Romilio et al., 2013), it seems to me that there is a fundamental flaw with the hypothesis upheld in the most recent paper (Romilio and Salisbury, 2014) that any or many of the tracks at the Dinosaur Stampede at Lark Quarry Conservation Park were formed underwater, and that is this:

    How did the water level change without disturbing the site?

    The reaction rim to the left of one of the large track maker's…

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    1. Anthony Romilio

      PhD; Research assistant at University of Queensland

      In reply to Stephen Poropat

      Hi Stephen,

      Thanks for your comments on various selected aspects of our three papers on Lark Quarry. There is a popular misconception about the preservation of fossils and the importance of water. Certainly when I walk along the sandy beaches of Iluka or Ballina in NSW, the wave action can destroy my footprints almost as soon as my feet exit them. The only impression that remains is the one in my mind telling me ‘footprints and water are a bad mix…. at least in this environment’. This is true for…

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    2. Stephen Poropat

      Palaeontologist

      In reply to Anthony Romilio

      Hi Anthony,

      Paragraph by paragraph:

      First: No real issue here – the nature of the sediment is paramount, no question. Finer-grained sediments, or sediments with a mixture of grain sizes including fine material, would be ideal, as would low energy environments.

      Second: Yes, swim traces exist, and in many cases must have been consolidated whilst still submerged.

      Third: I’m not questioning that.

      Fourth: Xing et al. (2013) note that invertebrate traces indicative of a non-marine shallow water environment…

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