Late Barremian Heteroceratidae Hyatt 1900 (ammonoidea), from the Sarcheshmeh Formation (KoppehDagh Basin, Northeast Iran): biostrartigraphy and paleobiogeoraphy

Some representative taxa of the Family Heteroceratidae from the Sarcheshmeh Formation are studied. These are: Heteroceras cf. colchicus Djanelidze, Heteroceras spp., Martelites cf. tenuicostatus (Kakabadze), Martelites securiformis (Simonovich, Bastevich and Sorokin), Martelites cf. tinae (Eristavi), Martelites sp.1, Martelites sp. 2, Argvethites sp., Imerites sparcicostatus Rouchadze and Paraimerites sp. These indicate a Late Barremian age. The Imerites giraudi and Martelites securiformis Biozones are proposed for the Upper Barremian Sub-Stage in the Koppeh Dagh Basin. The paleobiogeographic distribution of the Heteroceratidae during Late Barremian is discussed.