The Lark Quarry Trackway: Thulborn Strikes Back

UPDATE: I made a slight mix up when writing this article last week. I have stated that Thulborn, 2013 is responding to the claims of Romilio et al. 2012. This is actually incorrect. The paper to which Thulborn is responding is Romilio and Salisbury, 2011, where they dispute the identity of the large track maker at Lark Quarry and its consequences for the interpretation of the trackway. Thulborn has not yet responded to the new claims in Romilio et al. 2013, although he may do so in future. The core message of the article however is still the same. Romilio et al. do not believe that the trackway at Lark Quarry represents a dinosaur stampede, whereas Thulborn maintains it does. This intriguing topic will no doubt continue to provide ample material for debate in the years to come. This article has been edited from its original and second versions. For anyone who wants to see the original version, email me at the address at the top of the blog.

Regular readers of this blog (if there is such a thing) may recall that I wrote an article about a new paper by Romilio & Salisbury where they disputed the claims made by Tony Thulborn, who stated that the dinosaur trackways at Lark Quarry, Queensland were made by stampeding dinosaurs. In their paper they proposed that in fact the trackways were made at different times and showed dinosaurs crossing a river.

Perhaps a stampede after all? Thulborn certainly still seems to think so. Image from abc.net.au.
Perhaps a stampede after all? Thulborn certainly still seems to think so. Image from abc.net.au.

Now, Thulborn has responded to the claims made by Romilio & Salisbury, 2011, rejecting their analysis. In his rebuttal, Thulborn criticises their application of the multivariate analysis method, pointing out that they didn’t actually compare trackways of ornithopods and theropods but rather studied a single trackway, meaning that the only variation they could obtain would be between the individual tracks themselves. He also states that the multivariate analysis “appears to be based on fabricated data and is, therefore, worthless”.  The outlines of these tracks would have also deteriorated over time (Thulborn and Wade, 1984).

Thulborn also takes issue with how Romilio et al. have portrayed Thulborn’s initial interpretation of the site as a prey-pursuit scenario. Thulborn makes the distinction that he has never said it was this particular scenario (except when explicitly speculating), but rather that it was merely a stampede in general, regardless of the identity of the large track maker. Indeed, he argues that the whole premise of the recent paper by Romilio et al. seems to be to declare the larger tracks were in fact made by a large ornithopod, a fact that Thulborn declares is a “separate matter of secondary interest”.

So is the trackway at Lark Quarry evidence of a dinosaur stampede or not? Well, it depends on who you ask at the moment! Further study will no doubt show which of the two parties were closest to being correct. This debate is sure to continue; I’ll keep you all updated when the next developments arise!

References

Romilio A, S. W. Salisbury (2011) 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: 135-142.

Romilio A, Tucker, R. T. and S. W. Salisbury (2013): Reevaluation 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.

Thulborn, R.A. (2013): Lark Quarry revisited: a critique of methods used to identify a large
dinosaurian track-maker in the Winton Formation (Albian–Cenomanian), western Queensland, Australia, Alcheringa: An
Australasian Journal of Palaeontology, DOI:10.1080/03115518.2013.748482

Thulborn, R. A., and M. Wade. 1984. Dinosaur trackways in the Winton
Formation (mid-Cretaceous) of Queensland. Memoirs Queensland
Museum 21:413–517.

Why did the dinosaur cross the river? Because it wasn’t a stampede.

One of Australia’s best known dinosaur sites, the Dinosaur Stampede National Monument at Lark Quarry, near Winton, Queensland has just been dramatically reinterpreted in a new paper published in the Journal of Vertebrate Paleontology.  The site, which was covered by a purpose built building in 2002 and placed on the Australian National Heritage List in 2004 preserves over 3000 individual tracks that, until recently, were believed to demonstrate evidence of a ‘jumanji-esque’ dinosaur stampede.

Where these tracks made by fleeing dinosaurs of were they trying to cross a river? Image from environment.gov.au
Were these tracks made by fleeing dinosaurs or were they trying to cross a river? Image from environment.gov.au

The new paper, by Anthony Romilio (University of Queensland), Ryan Tucker (James Cook University) and Steven Salisbury (University of Queensland) puts forward a rather different hypothesis: the tracks represent a river of varying depth that dinosaurs often had to cross.

The orthodox spin on the story identifies two ichnotaxa (taxa known only from their tracks) as the track makers. Wintonopus, a small ornithopod and Skartopus, a small theropod. This was actually used as evidence of ‘mixed herding’ where small herbivores and carnivores hung around together as protection against larger predators Thulborn and Wade (1979, 1984, 1989).

Romilio et al. disagree with this interpretation. they claim that there is in fact only a single track maker present, which would be named as Wintonopus as it was named first, with Skartopus becoming a junior synonym. They also failed to find any evidence of a single mass of running individuals leaving them with their own opinion on what was going on here. “The presence of swim traces, long stride lengths, and preferred trackway orientation indicates that the majority of Lark Quarry trackmakers moved downstream and were current assisted. The paleo-water depth would have had to vary in order to allow different-sized buoyed trackmakers to contact the substrate, indicating that animals passed through the area at different time intervals. In the absence of evidence for the single mass of running terrestrial trackmakers, we consider that Lark Quarry is not representative of a ‘dinosaurian stampede.'”

A more accurate picture? Image by Anthony Romilio.
A more accurate picture? Image by Anthony Romilio.

So, which view is more accurate? Only time, and further research will tell. But as there appears to be some friction between the authors of the new paper and Richard Thulborn (one of the authors of most of the earlier work on the trackways), one thing is for sure; this isn’t the last we’ve heard about the Lark Quarry trackway.

The paper is discussed in a little more detail by Brian Switek (@Laelaps) on his excellent blog Laelaps (one of the best palaeo blogs going).

References

Romilio A, Tucker, R. T. and S. W. Salisbury (2013): Reevaluation 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

Thulborn, R. A., and M. Wade. 1979. Dinosaur stampede in the Cretaceous of Queensland. Lethaia 12:275–279.

Thulborn, R. A., and M. Wade. 1984. Dinosaur trackways in the Winton
Formation (mid-Cretaceous) of Queensland. Memoirs Queensland
Museum 21:413–517.

Thulborn, R. A., and M. Wade. 1989. A footprint as a history of movement; pp. 51–56 in D. D. Gillette andM.G. Lockley (eds.),Dinosaur Tracks and Traces. Cambridge University Press, Cambridge, U.K.