Didactyl, tridactyl and tetradactyl theropod trackways from the Lower Jurassic of Morocco: evidence of limping, labouring and other irregular gaits

Abstract

Two theropod trackways with alternating long–short pace lengths and a didactyl theropod trackway were discovered from Ait Blal tracksite situated in central High Atlas Mountains, Morocco. They are described here together with other tridactyl and tetradactyl footprints. The track-bearing bed belongs to the Lower Jurassic (Pliensbachian) Aganane Formation. One of the theropod trackways with alternating pace lengths indicates locomotion by a limping dinosaur. In this trackway, the pathological irregularities in the morphology of right footprints suggest that the trackmaker had injured its right foot. Another trackway with alternating pace lengths suggests the accidental problem while walking of theropod trackmaker. The morphology of the didactyl theropod trackway may be attributable to a dromaeosaurid or dromaeosaurid-like trackmaker whose body fossil remains have not been reported from the Jurassic. If the trackmaker of the didactyl prints was a dromaeosaurid, the discovery supports the idea that dromaeosaurid dinosaurs had early origins and also are ancestral to birds.

Keywords:

• limping
• didactyl
• footprint
• dinosaur
• Lower Jurassic
• Morocco

Acknowledgements

This study had been executed using the data taken during cooperative works of one of the authors (Ishigaki) for Moroccan Ministry of Energy and Mines with Japanese Overseas Cooperation Volunteers (JOCV). J. Jenny and J.-A. Jossen greatly helped S.I. to begin and continue the work. M. Bensaid, M. Dahamani, D. Nabil and all colleagues, technicians, drivers and assistants of the Moroccan ministry kindly supported S.I. Two reviewers kindly gave us constructive comments. The authors express sincere thanks to all those concerned.

Notes

Additional information

Notes on contributors

Martin G. Lockley

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