Late triassic spinicaudatan crustaceans from southwestern Poland

摘要

An assemblage of well-preserved spinicaudatan crustaceans ("conchostracans") is described from lacustrine late Carnian claystone at Krasiejow in southwestern Poland. Their shell microstructure is similar to that in extant spinicaudatans. Five species identified there are assigned to the genera Laxitextella, Menucoestheria (first record in the European Triassic), and Menucoestheria bocki sp. nov. and Krasiestheria parvula gen. et sp. nov. are erected. Specimens of Laxitextella laxitexta are the most abundant, comprising nearly half of the assemblage, those of Menucoestheria bocki one quarter, Laxitextella sp. A, Menucoestheria? sp., and Krasiestheria parvula form a minor component. Their ecological setting was probably similar to Recent relatives: temporary ponds of fresh water. The Late Triassic fauna in the German part of the same basin is closely similar to that in Poland. In Europe, the stratigraphic range of Laxitextella laxitexta is limited to the Middle Keuper (middle-late Carnian).