Elongatespiniferitescysts from North Atlantic bottom sediments

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Abstract
Elongate forms of Spiniferites are a characteristic feature of dinoflagellate cyst assemblages from north‐temperate and arctic environments. Assemblages from the Firth of Forth, Scotland; the Norwegian Sea; and the Barents Sea are described and illustrated to document the variation in morphology of these cysts, particularly in the development of the parasutural membranes. Although clearly elongate, these Spiniferites cysts may be distinguished both qualitatively and semi‐quantitatively from each other those from the Norwegian Sea are usually smaller with stouter processes, whereas those from the Barents Sea possess more highly pronounced parasutural membranes than the Firth of Forth forms. It is suspected that either a series of ecophenotypes is present or that there is some morphological gradient within the group. All the cysts described have an identical paratabulation and are, for the moment, assignable to the dinoflagellate Gonyaulax spinifera (Claparède & Lachman) Dies‐ing. The significance of these observations for the fossil record is potentially important in both the recognition of species and the possibility of increasing the usefulness of paleoecological analysis.