Tortuous trackways: evidence and implications of deviations, turns and changes in direction by dinosaurian trackmakers

ABSTRACT

Dinosaur trackways that show changes in direction are reported from Jurassic and Cretaceous sites in North and South America, Europe and Asia. Such changes in direction can be defined as tortuosity, and categorised in 45° quadrants. To date only six tortuous theropod trackways have been reported with changes in direction exceeding ¼ -¾ turns (~ 45° ^– ~135°). Likewise, six tortuous sauropod trackways show turns between ~ 65° and ~180°, and two of these show turns of more than 180°, thus crossing their own trackways. Dinosaur trackways with measured deviations between ~20° and 30° are also commonly reported. The reasons for trackway tortuosity cannot be inferred confidently, although a vast, potentially relevant biological cybernetics literature exists on possible extrinsic and intrinsic influences on directional changes. These are explored and listed as multiple working hypotheses. The potential to find tortuous trackways is inferred to increase with the size of track-bearing exposures. The lack of empirical information on tortuous trackways registered by large extant tetrapods, and the extrinsic environmental and or intrinsic behavioural reasons for such tortuosity, needs to be further explored and better understood as a step towards improved interpretation of the behaviour of extinct dinosaurian trackmakers.

KEYWORDS:

• Dinosaurs
• tortuosity
• ichnology
• biological cybernetics

Acknowledgments

We thank Anthony Romilio, the University of Queensland, Brisbane, Australia, and an anonymous reviewer for their reviews and helpful suggestions.

Disclosure statement

No potential conflict of interest was reported by the authors.