In an extraordinary discovery fueled by little more than a set of ancient footprints, paleontologists working in Canada have identified a previously unknown species of armored dinosaur, one that wielded a club-like tail.
The 100-million-year-old fossilized footprints, uncovered at two separate sites nestled within the rugged expanse of the Canadian Rockies, have offered a rare and valuable glimpse into prehistoric life during the Cretaceous period.
This remarkable find sheds light on an elusive chapter in the history of ankylosaurs — the family of heavily armored, herbivorous dinosaurs known for their distinctive body armor and, in some species, formidable tail clubs.
According to the researchers, ankylosaurs can be divided into two primary groups. Nodosaurid ankylosaurs, one branch of this family, were characterized by their flexible tails and four toes on each foot. On the other hand, their close relatives, ankylosaurid ankylosaurs, were notable for possessing a rigid, sledgehammer-like tail club and having just three toes.
What makes this discovery especially significant is the nature of the tracks themselves. While ankylosaur footprints are not uncommon in North America, most previously identified tracks — including those attributed to the species Tetrapodosaurus borealis — featured four toes. In contrast, these newly uncovered footprints have only three, marking the first known example of ankylosaurid ankylosaur footprints anywhere in the world. This detail provided a crucial clue in identifying the type of dinosaur that left them behind.
The newly identified species has been formally named Ruopodosaurus clava, a name that translates to “the tumbled-down lizard with a club or mace.” The name pays homage both to the mountainous, rugged environment where the tracks were discovered and to the defining clubbed tails of these formidable dinosaurs.
The groundbreaking research, detailing the find and its implications, was recently published in the Journal of Vertebrate Paleontology. While the physical appearance of the dinosaur that made these tracks remains speculative, researchers have drawn informed conclusions based on its footprints and what is known about similar species.
“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 meters long, spiky and armored, and with a stiff tail or a full tail club,” explained Dr. Victoria Arbour, curator of paleontology at the Royal BC Museum.
“Ankylosaurs are my favorite group of dinosaurs to work on, so being able to identify new examples of these dinosaurs in British Columbia is really exciting for me,” he added.
The discovery came about through a collaboration between Dr. Arbour and Dr. Charles Helm, a scientific advisor at the Tumbler Ridge Museum. Dr. Helm had long noted several trackways of three-toed ankylosaurs in the Tumbler Ridge area and, intrigued by their unusual characteristics, invited Dr. Arbour to collaborate on the study during a visit in 2023.
The tracks themselves date back to the mid-Cretaceous period, approximately 100 to 94 million years ago, a time when Earth’s landscapes were vastly different and dinosaurs roamed in abundance. Curiously, no ankylosaurid bones have been found in North America from about 100 to 84 million years ago, creating a perplexing gap in the fossil record.
For years, paleontologists speculated whether ankylosaurids had vanished from the continent during this interval. However, the newly discovered footprints provide concrete evidence that these armored giants persisted in North America throughout this enigmatic period.
Moreover, this finding reveals that both types of ankylosaurs — the nodosaurids with their flexible tails and four toes, and the ankylosaurids with their distinctive three-toed footprints — inhabited the same region during that era. The coexistence of these two groups paints a richer, more complex picture of dinosaur diversity and ecosystem dynamics in prehistoric Canada.
“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,” noted Dr. Helm.
The discovery also emphasizes the paleontological importance of the Peace Region of northeastern British Columbia, a treasure trove for dinosaur fossils and tracks.
“This study also highlights how important the Peace Region of north-eastern BC is for understanding the evolution of dinosaurs in North America—there’s still lots more to be discovered,” added Dr. Arbour.
As research continues, these fossilized footprints serve as enduring reminders of the untold stories still hidden within Canada’s ancient landscapes, and the dedicated scientists determined to uncover them.
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