Lower and Middle Oxfordian ammonite biostratigraphy at Zalas in the Cracow Upland

Abstract

The succession of ammonites collected bed-by-bed in three Lower to Middle Oxfordian sections at the Zalas quarry in the Cracow Upland, Southern Poland, indicates that the Lower Oxfordian strata are thin and stratigraphical1y condensed; they include the bukowskii, costicardia, and cordatum Subzones. The investigated sections include also the lowermost part of the Middle Oxfordian, viz. the tenuicostatum Subzone. The latter subzone yielded some cardioceratids unknown thus far from Poland, namely Cardioceras (Subvertebriceras) densiplicatum Boden and C. (Scoticardioceras) serrigerum (Buck.). Some new taxa representative of the subgenera Cardioceras, Plasmatoceras, and Scoticardioceras are de-scribed from the strata close to the Lower/Middle Oxfordian boundary.