LATE DEVONIAN AND EARLY MISSISSIPPIAN ECHINODERMS FROM CENTRAL AND NORTHERN IRAN

Abstract

New Devonian (Frasnian and Famennian) crinoids are described from central and eastern Iran and a new Mississippian (late Tournaisian) echinoderm fauna is described from the south flank of the Alborz Mountains of northern Iran. Both the Devonian and Mississippian echinoderms were living in a carbonate shelf basin on the northern flank of Gondwana at approximately 30° south latitude.The geographic ranges of Hexacrinites and Eutaxocrinus are extended onto the northern margin of Gondwana and add to the sparsely known Famennian crinoids. The Mississippian fauna is dominated numerically and in diversity by cladids, unlike most late Tournaisian faunas that are dominated by camerates in numbers, if not diversity. The late Tournaisian fauna is most similar to a coeval fauna from southern Iran, both of which have a noted lack of actinocrinitids and rare platycrinitids. It also shows similarity with Tournaisian faunas of western North America with four common genera.New species introduced are: Hexacrinites persiaensis, Eutaxocrinus risehensis, Dichocrinus damghanensis, Amabilicrinus stellatus, Bridgerocrinus alborzensis, Bridgerocrinus semnanensis, Paracosmetocrinus mobarakensis, Decadocrinus clypeus, and Palaechinus iranensis.