The early collecting history of dinosaurs and other fossil vertebrates in Western Canada during the 1870s and 1880s is poorly documented. Initial finds were made by the British North American Boundary Commission and the Geological Survey of Canada in modern Saskatchewan and Alberta but, beyond a few well-publicized examples, little is known about precisely what was found and where. Much of the collected material is now housed in the collections of the Canadian Museum of Nature in Gatineau, Quebec, and a recent survey of these historic finds allows for the first comprehensive narrative regarding their identity and procurement. The collection is heavily biased towards vertebral centra and phalanges, reflective of both taphonomic and collecting biases. Given current understanding of Upper Cretaceous assemblages of North America, ornithomimids and small theropods are overrepresented, whereas ceratopsids and ankylosaurs are underrepresented. Fossils from the Belly River Group are best represented, after repeated visits to the areas of present-day Dinosaur Provincial Park and Ross Coulee near Irvine, Alberta. Taxonomic identification of the material has yielded numerous first Canadian occurrences, in addition to some first global occurrences. The latter include the first ever occurrences of Caenagnathidae (1884) and Thescelosauridae (1889). The Upper Cretaceous fossil record of Western Canada is among the richest in the world, and has been thoroughly studied over the last century. These fossils have informed our understanding of dinosaur behaviour, taphonomy, ecology, diversity dynamics, and extinction, among other aspects. But, like the animals themselves, the story of Canada's dinosaur-hunting legacy had humble beginnings—a story that has not been fully revealed before now.

Modern North American carnivorous mammal assemblages consist of species from a single clade: the Carnivora. Carnivorans once coexisted with members of other meat-eating clades, including the creodonts (Hyaenodontida and Oxyaenida). Creodonts, however, went extinct in North America during the late Eocene and early Oligocene, potentially due to niche overlap and resource competition with contemporary carnivorans. In this study, we employ a community ecology approach to understand whether the dietary niches of coexisting creodonts and carnivorans overlapped during the late Eocene (Chadronian North American Land Mammal Age), a time when creodonts were dwindling and carnivorans were diversifying. We quantify niche overlap based on inferences of diet from carnassial tooth shape estimated using Orientation Patch Count, Dirichlet’s Normal Surface Energy, and linear dental measurements as well as from body mass for all species in the Calf Creek Local Fauna of Cypress Hills, Saskatchewan (Treaty 4 land). Although creodonts and carnivorans shared characteristics of their carnassial tooth shape, suggesting similar chewing mechanics and feeding habits, we find that marked differences in body size likely facilitated niche partitioning, at least between the largest creodonts and carnivorans. Calculations of prey focus masses and prey mass spectra indicate that only the smallest creodont may have experienced significant competition for prey with the coeval carnivorans. We suggest that the ultimate extinction of creodonts from North America during the late Eocene and Oligocene was unlikely to have been driven by factors related to niche overlap with carnivorans.