Ammonite and inoceramid bivalve faunas from the Davutlar Formation of the Devrekani–Kastamonu area, northern Turkey, and their biostratigraphical significance

The ammonite and inoceramid bivalve faunas of the Davutlar Formation of the Devrekani–Kastamonu area in central-north Turkey, are described. The formation yields an ammonite assemblage of Pseudophyllites indra (Forbes, 1846), Pachydiscus (Pachydiscus) haldemsis (Schlüter, 1867), Pachydiscus (Pachydiscus) oldhami (Sharpe, 1855), Didymoceras binodosum (Kennedy and Cobban, 1993), Bostrychoceras polyplocum (Roemer, 1841) and Baculites alavensis Santamaria Zabala, 1996. The inoceramid assemblage is Cataceramus subcompressus (Meek and Hayden, 1862), Cataceramus goldfussianus (d'Orbigny, 1846), Platyceramus vanuxemi (Meek and Hayden, 1860), Cataceramus cf. mortoni (Meek, 1876), Cataceramus pteroides (Giers, 1964), Cataceramus aff. barabini (Morton, 1834), Platyceramus pierrensis (Walaszczyk et al., 2001), “Inoceramus” convexus Hall and Meek, 1856, Cordiceramus heberti (Fallot, 1885), “Inoceramus” tenuilineatus Hall and Meek, 1856, “Inoceramus” borilensis Jolkicev, 1962, as well as some forms with no or equivocal specific affiliation. Both ammonite and inoceramid faunas suggest an early Late Campanian age for the formation, most probably Bostrychoceras polyplocum and Didymoceras donezianum ammonite Zones / Cataceramus subcompressus and “Inoceramus” tenuilineatus inoceramid Zones. Both ammonite and inoceramid assemblages are well represented throughout the Euramerican biogeographical region.