The oldest micro- and nannofossils of the ?Tithonian Lower Cieszyn Shales and detrital Cieszyn Limestones are dominated by redeposited calcareous benthic foraminifera and calcareous nannoplankton. These assemblages are similar to those of epicontinental seas or large shelf areas. The younger micro- and nannofossil pelitic part of the Berriasian Cieszyn Limestones and Valanginian Upper Cieszyn Shales are composed of low-diversity primitive agglutinated foraminiferids and calcareous nannoplankton that resemble coeval faunas and floras of the Tethys seas. The sequence of foraminiferal assemblages and the nature of the nannoplankton associations from the "Cieszyn Beds" reflect the subsidence or collapse of the NE European Platform margin, disappearance of shallow areas with carbonate sedimentation, and formation of a deep basin with turbidite sedimentation. These events may be related to the Neocimmerian orogeny and the worldwide regression at the Tithonian/Berriasian boundary.