Scientists have uncovered the first known footprints belonging to armoured dinosaurs with clubbed tails.
These 100-million-year-old fossilised tracks were found in two locations in the Canadian Rockies – Tumbler Ridge in British Columbia and north-west Alberta – revealing exciting clues about a group of dinosaurs called ankylosaurs.
Ankylosaurs were hefty, tank-like dinosaurs covered in bony armour. Scientists split them into two main groups: nodosaurids, which had flexible tails and four toes; and ankylosaurids, known for their heavy, sledgehammer-like tail clubs and only three toes.
While four-toed ankylosaur footprints have been found across North America before, these new three-toed tracks are the first confirmed evidence of ankylosaurids leaving their mark.
The newly identified dinosaur has been named Ruopodosaurus clava, meaning 'the tumbled-down lizard with a club/mace' – a nod to both the rugged mountain landscape where it was found and the dinosaur’s distinctive tail weapon.
Dr Victoria Arbour, a palaeontologist at the Royal BC Museum and an expert on ankylosaurs, co-led the study along with a team from the Tumbler Ridge Museum and the local UNESCO Global Geopark. Their findings were published in the Journal of Vertebrate Paleontology.
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“While we don’t know exactly what the dinosaur that made Ruopodosaurus footprints looked like, we know that it would have been about 5-6 metres long, spiky and armoured, and with a stiff tail or a full tail club," says Arbour.
“Ankylosaurs are my favourite group of dinosaurs to work on, so being able to identify new examples of these dinosaurs in British Columbia is really exciting for me.”
Dr Charles Helm, scientific advisor at the Tumbler Ridge Museum, had spotted several of these mysterious three-toed tracks in the area years ago. In 2023, he invited Dr Arbour to help investigate. They were joined by Eamon Drysdale, the museum’s curator, geoscientist Roy Rule, and the late Martin Lockley, a dinosaur track expert from the University of Colorado.
The footprints date to the mid-Cretaceous period, roughly 100 to 94 million years ago. Interestingly, no ankylosaurid bones from this time period have ever been found in North America – raising questions about whether they had disappeared during that era.
But these tracks prove that tail-clubbed ankylosaurs were still very much alive, thriving alongside their nodosaurid cousins.
“Ever since two young boys discovered an ankylosaur trackway close to Tumbler Ridge in the year 2000, ankylosaurs and Tumbler Ridge have been synonymous," says Helm.
"It is really exciting to now know through this research that there are two types of ankylosaurs that called this region home, and that Ruopodosaurus has only been identified in this part of Canada,”
“This study also highlights how important the Peace Region of northeastern BC is for understanding the evolution of dinosaurs in North America – there’s still lots more to be discovered,” says Arbour.
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