| Summary: | The early Eocene is an important time in Cenozoic history because it marked the height of global warming, coincident with significant reorganization of the mammalian biota. In North America, our understanding of mammalian diversity during this interval is largely limited to a fossil record south of the 49th Parallel. New discoveries in the early Eocene Driftwood Creek beds (Ootsa Lake Group), northern British Columbia (∼55°N) double the known diversity of Eocene mammals from this Canadian province and provide a window into the mammalian community that lived near the northernmost lake of the Okanagan Highlands, a series of Eocene lake deposits extending north-south from Republic, Washington, to Smithers, northern British Columbia. A diverse insect and fish fauna has been described from Okanagan Highlands Eocene lake shales, together with a diverse flora, interpreted as a cool upland forested landscape. We report the tapiroid cf. Heptodon and an erinaceomorph lipotyphlan Silvacola acares, gen. et sp. nov., from the Driftwood Creek beds. Presence of cf. Heptodon is consistent with the late early Eocene age of the Driftwood Creek beds determined by radiometric dating and palynology. Heptodon is otherwise known from Eocene localities in Wyoming and Colorado as well as Ellesmere Island in the High Arctic, whereas erinaceids are recorded from late Paleocene sites in Alberta, Saskatchewan, and the U.S. Western Interior and are relatively uncommon at Eocene sites in the U.S. Western Interior. Occurrence of cf. Heptodon at Driftwood Canyon supports the hypothesis proposed by others that tapiroids are proxies of densely forested habitats.
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