Limbodinium, a new dinoflagellate genus from the Jurassic of Western Europe

Abstract

The paratabulation and morphology of the Jurassic dinoflagellate cyst species Dinopterygium absidatum Drugg 1978 are demonstrated to be substantially different from that of the type species of Dinopterygium, D. cladoides Deflandre 1935. Dinopterygium absidatum defines a morphotype that is sufficiently distinctive to justify the erection of a new, as yet monotypic genus, Limbodinium Riding. A revised diagnosis for the species Limbodinium absidatum is given on the basis of new observations on its morphology.

The removal of D. absidatum from Dinopterygium means that the geological range of unequivocally quinqueform dinoflagellate cysts is now confined to the late Early Cretaceous to Neogene. The eight known quinqueform cyst genera are preceded stratigraphically, and dominated numerically, by sexiform types; this sequence does not conform to a recently postulated evolutionary pathway.