The Upper Turonian–Lower Coniacian (Upper Cretaceous) ammonites from the condensed phosphate beds of Mangyshlak, NW Kazakhstan

Abstract

Eleven ammonites species are described from the condensed phosphate beds of Mangyshlak (in north-western Kazakhstan): Lewesiceras mantelli (Wright and Wright, 1951), Subprionocyclus neptuni (Geinitz, 1849), Prionocyclus spp., Allocrioceras angustum (J. de C. Sowerby, 1850), Hyphantoceras (Hyphantoceras) reussianum (d’Orbigny, 1850), Hyphantoceras (Hyphantoceras) cf. flexuosum (Schlüter, 1872), Eubostrychoceras (Eubostrychoceras) cf. saxonicum (Schlüter, 1875), Scalarites? bohemicus (Fritsch, 1872), Sciponoceras bohemicum bohemicum (Fritsch, 1872), Scaphites geinitzii d’Orbigny, 1850, and Scaphites kieslingswaldensis Langenhan and Grundey, 1891. They provide an incomplete record that spans at maximum upper Middle Turonian to Lower Coniacian and at minimum Upper Turonian to Lower Coniacian. Associated inoceramid bivalves span an interval from upper Middle Turonian (based on the known first occurrence of Inoceramus inaequivalvis Schlüter, 1872) to the lower and middle Lower Coniacian, based on the known last occurrence of Cremnoceramus crassus inconstans (Woods, 1912), in the lower and middle parts of the Lower Coniacian.