Early Cretaceous ammonites and dinoflagellates from the Western Tatra Mountains, Poland

Abstract

The first Early Cretaceous (Valanginian-Hauterivian) ammonite fauna from the lower part of the Kokieliska Marl Formation (Wkiekly Zleb Member) of the Lower Sub-Tatric (ICrana) Nappe, in the Lejowa Valley of the Tatra Mountains are described. The fauna is precisely placed in the succession and consists of five species: Olcostephanus densicostatus, Spitidiscus cf. cankovi, Criosarasinella cf. subheterocostata, Crioceratites primitivus, and Crioceratites con iferus and additionally an aptychusDidaydamellaptychus seranonis. Remarkable are the valves of anomiid bivalves attached to body chamber of large size heteromorph ammonite C. primitivus. Moreover, a variety of stratigraphically important organic-walled dinoflagellate cysts are recovered from this locality. Dinoflagellates: Cymososphaeridium validum, Citrulodinium vermiculatum, and representatives of Bourkidinium define the Upper Valanginian-Lower Hauterivian Sentusidinium sp. A Dinocyst Subzone of the Cymososphaeridium validum Zone. The character of deposits, the palynofacies, and associations of dinoflagellate cysts indicate a calm marine outer neritic environment.