ABSTRACT
Five rhynchonellid assemblages are recognized in the epicontinental, marine Upper Cretaceous of northern Bulgaria, below the end-Cretaceous extinction event. Ages of the assemblages were determined by associated macrofossils and/or by correlation with occurrences of studied rhynchonellid taxa in other regions. Available data fail to meet criteria necessary to establish a biozonal scheme, nevertheless these assemblages provided an alternative for dating lithostrati-graphic complexes, where other fossils were absent. Described are the Orbirhynchia mantelliana (Cenomanian), Cyclothyris difformis (lower-middle Cenomanian), Orbirhynchia reedensis (middle-upper Turanian), Cyclothyris globata (uppermost upper Santonian), and Septatoechia aff. baugasii (upper Campanian) assemblages of Cretaceous age.
