Brachiopods and echinoids from the lower Cenomanian of Koraćica (Kosmaj Mountain, central Serbia)

• Two brachiopod and nine echinoid taxa are revised from the Koraćica village, Serbia.
• Five echinoid species are recorded for the first time in Serbia.
• Palaeobiogeography and palaeoecology are taken in consideration.
• The Albian–Cenomanian boundary is defined based on large foraminifera and ammonites.

Two brachiopod species belonging to two genera, two families, and one order and nine echinoid taxa (five regular and four irregular) belonging to eight genera, seven families, and seven orders are revised and systematically described from reddish coarse-grained bioclastic packstones to rudstones of the Grab spring section (Kosmaj Mountain) of the Vardar Zone of central Serbia. The stratigraphic range and the palaeobiogeographic distribution are given for each species. Five echinoid species, “Cidaris” strombecki (Desor, 1858), Leptosalenia cf. prestensis (Desor, 1856), Tetragramma variolare subnudum (Agassiz, 1846), Conulus (Conulopyrina) vionneti (Desor, 1857), and C. (Conulus) castanea (Brongniart, 1822) are recorded from the lower Cenomanian of Serbia for the first time. Earlier on, the benthic macrofauna of the section has been assigned an Albian–Cenomanian age. Although the upper Albian–lower Cenomanian boundary is covered by debris, the presence of the lower Cenomanian larger foraminiferal zone [Orbitolina (Conicorbitolina) conica] allows to assign the lower part of the Cenomanian succession certainly to the lower Cenomanian. The O. (C.) conica Zone overlies the uppermost Albian planktonic foraminiferal Thalmanninella appenninica and the ammonite Puzosia planulata zones. Most of the brachiopods and echinoids are predominantly confined to the northern margin of the Tethyan realm and some species are also known from the southern margin of the Tethys and from north-eastern Brazil. The distribution patterns of the taxa were probably influenced by east-west directed currents during the early Cenomanian time. The identified taxa are associated with other macrofaunal elements such as ammonites, bivalves, gastropods, and corals. The presence of stenohaline groups document euhaline conditions. The high degree of fragmentation, disarticulated bivalves, and the upward oriented of the adoral surfaces of most echinoids suggest that the organisms lived in moderately agitated subtidal environments and suffered post-mortem transport.