Ostracod assemblages from the Middle Jurassic of NW Germany with special reference to the Sowerbyi ammonite Zone (Early Bajocian, Jurassic)

摘要

Middle Jurassic (Aalenian to Bajocian) ostracod assemblages from a temporary motorway outcrop in NW-Germany (Braunschweig area) are investigated in detail. Highest abundances and species diversity are observed in the upper Lower Bajocian interval that can be assigned to the Sowerbyi ammonite Zone. Sediments of Bajocian age are stratigraphically underexplored in NW Germany. The well preserved microfaunal assemblages compares closely with ostracod associations reported from time-equivalent deposits of England. The following new ostracod subgenus, species and subspecies are described: Dolocythere tuberculata sp. nov., Southcavea (Saxosouthcavea subgen. nov.) extendata sp. nov. Southcavea (Saxosouthcavea subgen.nov.) bartenbrandi sp. nov., Southcavea (Saxosouthcavea subgen. nov.) malzi malzi sp. et subspec. nov., Southcavea (Saxosouthcavea subgen. nov.) malzi reticulata subsp. nov., Kinkelinella circumcostata sp. nov., Ljubimovella debilicostatus sp. nov., Vernoniella tenuipora sp. nov., and Balowella crassicostata sp. nov. The new genus Superpendicythere and its type species S. binodosa sp. nov. are also described. In connection with the new description of Balowella crassicostata sp. nov., related species are discussed and newly illustrated.