The first hadrosaurid trackway from the horseshoe canyon formation (campanian/maastrichtian) of Alberta, Canada

Abstract

The Horseshoe Canyon Formation has provided a wealth of vertebrate skeletal fossils over the past 100 years of collection. Vertebrate trace fossils such as footprints and trackways, however, have been markedly underrepresented. Trackways can provide a wealth of information regarding behaviour and soft tissues reflective of autopodial anatomy. Discovery of several giant, high-fidelity ichnites in series from the Morrin Member represents the first definitive dinosaur trackway reported from the Horseshoe Canyon Formation. The trackway is composed of three footprint casts in series, alongside 22 associated ichnites. The ichnites were formed in soft sediment molds along a non-uniform walking surface. The deep substrates allowed for the preservation of both the plantar surface and dorsal components of the trackmakers’ feet. Some ichnites show soft tissue morphologies like interdigital webbing, toe pads, and skin impressions. Presence of these features and small kidney-shaped forelimb prints allow referral to Hadrosauropodus langstoni. The preservation of the trackway demonstrates asymmetries useful for comparison of the relief and impression surfaces of prints using both discrete and morphometric characteristics, improving confidence in identifying partial or isolated Hadrosauropodus prints of various modes of formation.

Keywords:

• Ornithopoda
• Ornithischia
• skin impression
• Ichnology
• Dinosaur
• Ichnite
• cast

Acknowledgments

Fieldwork to excavate the Lone Spruce Tracksite and collect one of the tracks was funded by NSERC, Vanier Canada, the Alberta Historical Resources Foundation, the Alberta Lottery Fund, and the Dinosaur Research Institute, including its donors and committee members. We would like to thank Don Rae for providing funds to offset costs for the drone that we used to photograph the tracksite. We thank UALVP preparators, Clive Coy and Robin Sissons, and RTMP preparator, Darren Tanke for their advice on preparation of concretionary ichnites. We thank the volunteers of the UALVP field crews for the field seasons of 2017–2019. Dr. Andrew Dufrane provided us with date estimates for the tracksite, although they did not make it into the final manuscript. We thank Matteo Belvedere and an anonymous reviewer for their useful comments and feedback during the first round of revisions, and Jens N. Lallensack and James O. Farlow for their input and suggestions for the second round of revisions, both of which greatly improved the quality of this manuscript. We also thank the editor at Ichnos, Hendrik Klein for their useful feedback and assessment of our manuscript for publication. GFF is funded by a Banting Postdoctoral Fellowship.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Dinosaur Research Institute.