A small outcrop belonging to an unnamed shale unit in the Buffalo Head Hills of north-central Alberta has yielded marine microfossils of Senonian, most probably Campanian, age.The foraminiferal fauna, including Haplophragmoides fraseri, Verneuilinoides bearpawensis, Praebulimina carseyae and Cassidella tegulata, suggests equivalence with that of the upper Campanian Bearpaw fauna of southern Alberta.The radiolarian assemblage includes Spongurus (Spongurantha) sp., Spongodiscus (Spongodisus) sp. cf. S. (S.) renillaeformis, Spongostaurus sp., Spongotripus (Spongotripus) sp. cf. S. (S.) morenoensis and Dictyomitra (Dictyomitra) multicostata, which are present in the Bearpaw Formation of southern Alberta, and in an interval of the Schrader Bluff Formation of northern Alaska, considered middle Senonian in age.Among the dinoflagellates recorded from the outcrop, three species of Dinogymnium – D. acuminatum, D. longicornis and D. sibiricum, and four species of Deflandrea – D. granulifera, D. minor, D. spectabilis and D. victoriensis are restricted to strata of Senonian age (inclusive of Maestrichtian Stage). Of this group, Dinogymnium longicornis, Deflandrea granulifera and D. spectabilis are present in the Bearpaw Formation of southern Alberta. The dinoflagellate assemblage has four species in common with that of the Senonian or younger beds in western Siberia.The pollen assemblage is dominated by species of Aquilapollenites – A. dolium, A. trialatus and A. turbidus – strongly indicative of a Campanian age. A megaspore, Balmeisporites rarus, suggests a Senonian age.The microfossil assemblage provides corroborative evidence in support of J. A. Jeletzky's hypothesis that a marine connection existed between the Arctic and Western Interior regions through northern Alberta during the Santonian and Campanian.