| Although shark teeth are the most abundant vertebrate fossil in the marine record, they are not well documented from polar regions. A collection of over 8,000 shark teeth from Eocene strata of the Eureka Sound Formation in Aulavik National Park on northern Banks Island, Northwest Territories, Canada (∼74°N) presents a great opportunity to gain information about the coastal paleobiology and paleoecology of Canada's western Arctic region.;Shark teeth were sorted and identified by comparison to specimens in museums and a private collection as well as published descriptions of other shark faunas. Three genera of sharks were identified: the sand tigers (family Odontaspididae) Striatolamia, Carcharias (at least two species), and the extinct sharpnose shark (Carcharhinidae) Physogaleus. These shark taxa, when considered alongside the fossils of turtle, bony fishes, ray, and plants also present, indicate a mild, warm-temperate environment in the western Canadian Arctic during the Eocene. This is consistent with the research of others in correlative strata of the Eureka Sound Group in Canada's eastern Arctic, and helps to provide a more regional picture of the Arctic paleoclimate.;The low shark diversity observed is consistent with a low-salinity deltaic environment that has been interpreted from the sediments. Additionally, the sizes of shark teeth collected may provide insight into the lives of the sharks that inhabited the area. A predominance of small teeth (≤15mm) whose sizes correspond to baby and subadult sharks, and a scarcity of large teeth that correspond to adult teeth may indicate a shark nursery area. These observations are consistent with the known habit of modern sand tigers to use reduced-salinity environments as nursery areas. |
