انتشار چينه شناسي و جغرافيايي بازوپايان نيكونليد در دونين پسين (فرازنين ) ايران

Stratigraphical and Geographical Distribution of Rhynchonellida in the Late Devonian (Frasnian) of Iran

Frasnian deposits are very widespread in Iran (Central Iran and Alborz Range) and brachiopoda (specially Rhynchonellida) are considered as their index fossils. The genera: Cyphoterorhynchus, Ripidiorhynchus, Paropamisorhynchus, Coeloterorhynchus, Lateralatirostrum and Ladogilina are Frasnian Rhynchonellid of Iran, that their geographic and stratigraphic distribution were studied, and their biozonations were based on the Brice (1977) in Afghanistan. Two genera: Ripidiorhynchus and Cyphoterorhynchus have more species as well as wide distribution. Hence they have more biostratigraphicl importance than other genera. Also the Coeloterorhynchus genus has shorter age extent (Late Frasnian) than other genera. Consequently, the Rhynchonellida have very biostratigraphical applications in Iran and even in the Word, because of their extensive geographic distribution and short age extent.