Representatives of the genus Belemnitella of Bulgaria (Upper Cretaceous)

Abstract

Some 11 taxa are described from the species-group of Upper Cretaceous belemnites, belonging to the genus Belemnitella. Palaeontological description is preceded by short stratigraphis notes and data on the rostrum morphology. Following international zonation standards, the species described are characteristic of different levels of the Campanian - ranging from the upper part of the Lower Campanian to the Lower Maastrichtian. In Bulgaria they occur at one and the same stratigraphic level, assumed to be Upper Campanian. This is usually proved by the presence of Belemnitella mucronata minor and B. langei langei, as well as Bostrychoceras polyplocum, zonal ammonite species for the Upper Campanian B. conica conica and B. bulgarica also found in the Lower Maastrichtian. The belemnites appear in larger numbers in phosphatised horizons, related 10 the formation of hard grounds in chalk and chalk-like limestone. The rostrum morphology is considered in terms of the significance of the individual characteristics for taxonomy. Statistical analyses have been made-one-variant and two-variant ones of several scores of specimen. Two new species and an unnamed one are described.