An Arctic nursery
Seventy-three million years ago, this region of Alberta was a coastal plain located at a paleolatitude of approximately 62-72° North, well inside the Arctic Circle. During the Late Cretaceous, the climate was warmer than today, but the high latitude still meant months of winter darkness and the possibility of snow. For decades, paleontologists assumed that dinosaurs migrated south to escape these harsh conditions, much like modern caribou. The discoveries within the Wapiti Formation challenge that assumption directly.
Fossil evidence shows that herds of hadrosaurs, or duck-billed dinosaurs, lived here and reproduced here. The important evidence comes from the discovery of nesting grounds containing the remains of perinatal (newborn) and very young juvenile hadrosaurs alongside adults. These tiny dinosaurs were too small and undeveloped to have undertaken a thousand-kilometer migration south after hatching. Their presence strongly indicates that these polar dinosaurs were year-round residents, adapted to a life of extreme light and dark cycles. This site is the most northern evidence of dinosaur nesting found in North America.
Life on the polar floodplain
The Wapiti Formation preserves a complex ancient ecosystem. The environment was a low-gradient, waterlogged alluvial plain with high-sinuosity rivers, oxbow lakes, and marshes, located about 300 kilometers northwest of the Bearpaw Sea, an inland sea that once split North America. The fossil assembly includes hadrosaurs like Edmontosaurus, but a diverse community of other dinosaurs.
Predators were a constant threat. A large number of teeth from the small troodontid theropod Troodon have been found in direct association with the remains of baby hadrosaurs, suggesting a predator-prey relationship. Larger tyrannosaurids, relatives of T. rex, also roamed these polar forests, along with dromaeosaurids such as Saurornitholestes. The fauna also included the horned dinosaur Pachyrhinosaurus, ankylosaurs, and pachycephalosaurs. Beyond dinosaurs, the formation has yielded fossils of fish, turtles, squamates (lizards), and early mammals, painting a detailed picture of life in the Cretaceous Arctic. The study of these nesting sites and the surrounding fauna shows dinosaur reproductive behavior and their surprising adaptability to challenging environments.