Late Albian ammonites from Koraćica (Kosmaj Mountain, central Serbia) and their biostratigraphic implications

Nineteen late Albian ammonite taxa and one nautiloid species belonging to eight genera and four families are systematically described from reddish coarse-grained bioclastic packstones to rudstones of the Grab well section (Kosmaj Mountain), Vardar Zone of central Serbia. Among the identified taxa, the nautiloid Eutrephoceras cf. clementianum (d'Orbigny, 1840) and seven ammonite taxa, Tetragonites rectangularis Wiedmann, 1962, Puzosia provincialis (Parona and Bonarelli, 1897), Bhimaites cf. pinguis (Crick, 1907), Beudanticeras (Beudanticeras) cf. beudanti (Brongniart, 1822), Hysteroceras cf. pseudocornutum Spath, 1934, Mortoniceras (Subschloenbachia) rostratum (J. Sowerby, 1817), and M. (S.) cf. perinflatum (Spath, 1922) are recorded for the first time from Serbia. The identified taxa are typical representatives of the Tethyan faunal province. Ammonite taxa provide the first reliable biostratigraphic dating of the Grab well section of central Serbia. The reddish coarse-grained bioclastic packstones to rudstones (a 0.5-m-thick lens) belong to the upper Albian, which is proven by ammonites of the uppermost Albian Mortoniceras rostratum and M. perinflatum zones and the early late Albian brancoceratines Hysteroceras orbignyi (Spath, 1922), H. choffati Spath, 1925, and H. varicosum (J. de C. Sowerby, 1824), which are equivalent to the M. pricei, M. inflatum, and M. fallax zones. The overlying 3.5 m of sandy packstones are assigned to the earliest Cenomanian based on the brachiopods Capillithyris capillata (d'Archiac, 1847) and Terebrirostra lyra (J. Sowerby, 1816), which characterize the lowermost Cenomanian Mantelliceras mantelli Zone. The upper part of the Grab well section (20 m in bedded silty marlstones and marly siltstones) is assigned to lower middle Cenomanian based on the presence of the Turrilites costatus Subzone.