Ancient Club-Tailed Dinosaur Footprints Rewrite North American Prehistoric Timeline

Scientists have uncovered the first-ever footprints of club-tailed armored dinosaurs in the mountains of British Columbia, challenging previous theories about dinosaur migrations and extinctions in North America.

The 100-million-year-old three-toed tracks, discovered across multiple sites near Tumbler Ridge, BC and northwestern Alberta, provide concrete evidence that tail-clubbed ankylosaurs roamed western Canada during a period when many paleontologists believed they had disappeared from the continent.

Named Ruopodosaurus clava — meaning “the tumbled-down lizard with a club/mace” — these newly identified footprints belong to ankylosaurid dinosaurs, the sledgehammer-tailed cousins of the more commonly found nodosaurid ankylosaurs.

“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 Dr. Victoria Arbour, curator of paleontology at the Royal BC Museum and lead author of the study published in the Journal of Vertebrate Paleontology.

What makes this discovery particularly significant is the number of toes preserved in the tracks. Unlike previously known ankylosaur footprints called Tetrapodosaurus borealis, which show four toes, these new tracks have only three — a characteristic unique to the tail-clubbed ankylosaurid dinosaurs.

The research fills a critical gap in North America’s fossil record. No skeletal remains of ankylosaurids had previously been found from approximately 100 to 84 million years ago, leading some paleontologists to theorize these armored giants had temporarily vanished from the continent.

“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, who specializes in the study of ankylosaurs.

The discovery required extensive collaboration between researchers from the Royal BC Museum, Tumbler Ridge Museum, Tumbler Ridge UNESCO Global Geopark, and the University of Colorado. Dr. Charles Helm, scientific advisor at the Tumbler Ridge Museum, had observed these distinctive three-toed ankylosaur trackways for several years before inviting Arbour to collaborate on their identification.

“Ever since two young boys discovered an ankylosaur trackway close to Tumbler Ridge in the year 2000, ankylosaurs and Tumbler Ridge have been synonymous. 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,” says Helm.

The research also provides compelling evidence that both major groups of ankylosaurs — the club-tailed ankylosaurids and the flexible-tailed nodosaurids — lived side by side in the same environments during the middle Cretaceous period, approximately 100 to 94 million years ago.

To identify the tracks, researchers employed photogrammetry, creating detailed 3D models from photographs. Some of the best-preserved specimens were found as fallen blocks that had tumbled from cliff faces, while others remain in their original positions along remote creek beds and riverbanks.

The unique three-toed pattern confirms these tracks were made by ankylosaurids, as ancestral state reconstruction analysis shows that the reduction from four toes to three is a distinctive characteristic of this dinosaur group. The team’s research indicates the Ruopodosaurus trackmaker was likely around 1.2 meters tall at the hip, similar in size to later ankylosaurids like Euoplocephalus and Scolosaurus.

What’s particularly remarkable is that several trackways at one remote location appear to run parallel without crossing, suggesting these heavily-armored dinosaurs may have traveled in groups — adding another layer to our understanding of ankylosaur behavior.

Beyond filling gaps in the fossil record, the discovery emphasizes the importance of trace fossils — footprints, burrows, and other marks left by ancient creatures — in understanding prehistoric ecosystems, especially in regions where skeletal preservation is poor.

For the Tumbler Ridge area, already recognized for its rich paleontological heritage, this discovery further cements its status as one of North America’s most important windows into the age of dinosaurs.