بعنوان يك شاخص در دونين پسين ايران و جهان RIPIDIORHYNCHUS اهميت بيواستراتيگرافي

The Stratigraphic Significance of Ripidiorhynchus Sartenaer, 1966 as an Index in the Late Devonian of Iran and the World

The genus of Ripidiorhynchus belongs to Rhynchonellida order, and its type species is the genus of Ripidiorhynchus livonicus (von Buch, 1834). The genus has twenty four species, and these species are distributed in different regions of the world such as: Iran, Afghanistan, Germany, Spain, USA, England, Northern Africa, Azerbaijan, Belgium, Tadjikestan, Turkey, Pamir, Czechoslovakia, Russia, France, Caucasus, Kazakhistan, Kirgizia, Poland and Ural, Tiana-Chan and Timan mountains. The age of Ripidiorhynchus in these regions is Early Frasnian - Middle Famennian. This genus in Iran has five species: Ripidiorhynchus barroisi, Ripidiorhynchus elburznsis, Ripidiorhynchus kermanensis, Ripidiorhynchus kotalensis, and Ripidiorhynchus minutissimus. These species have been found in Central Iran (Esfahan, Soh, Anarak, Kerman, Ozbak-Kuh) and Alborz (Central-Eastern Alborz) regions in Jeirud, Khoshyeilagh and Bahram Formations. The age of these species is Middle-Late Frasnian. Consequently, Ripidiorhynchus genus may be used as stratigraphic tool in a global scale, due to its relativly long-range age. In Iran, however, the genus can be used as a valuable stratigraphic tool, because of its short-range age and wild spread.