Middle Jurassic bivalves from Geographical Society Ø, North-East Greenland

The siliciclastic Bajocian–Bathonian Pelion Formation of Tværdal, Geographical Society Ø, East Greenland, is dominated by shallow-marine sandstones, which yielded 22 bivalve taxa representing 18 genera; these are described and figured here. The type species of the subgenus Strimodiolus, Modiolus (Strimodiolus) elongatus Fürsich, 1982, is a junior homonym of Modiola elongata Swainson, 1821 and is replaced by M. (Modiolus) milnelandensis nom. nov. Infaunal taxa dominate in terms of abundance and species richness, and several of the semi-infaunal (e.g., Strimodiolus, Cyrtopinna) and deep-burrowing (Pleuromya) bivalves are preserved in life position, suggesting periodical high sedimentation rates below the fair-weather wave-base during deposition of most of the formation.