The affinities of early oncocerid nautiloids from the Lower Ordovician of Spitsbergen and Sweden

Phthanoncoceras oelandense gen. et sp. nov. from the Kundan (Llanvirn) of Sweden and Valhalloceras floweri gen. et sp. nov. from the Cassinian (Arenig) of Ny Friesland, Spitsbergen are described and a new family, the Phthanoncoceratidae (Oncocerida) is proposed. The relationships of the Phthanoncoceratidae to the Oncocerida and Ellesmerocerida are discussed.