Ordovician Invertebrates from Jebel Qamar South,Dibba Zone,United Arab Emirates

A limited invertebrate fauna have been collected from the detached exotic blocks in the Dibba zone at Jebel Qamar South, United Arab Emirates. The Receptaculitacea species Cyclocrinus multicavus, the Orthoceratidae Orthoceras sp., and the Nileidae Nileus emiratus n. sp., have been identified. According to this fauna, a Middle Ordovician age could be assigned to the upper part of the Rann Formation and the lower part of the Ayim Formation, from which the described specimens have been obtained. The fauna indicates a deposition in a shallow shelf environment with open circulation. The prevailing palaeoclimatic conditions in the area in connection with the widespread Late Ordovician Saharan glaciations postulate that the nileids and the receptaculitids probably tolerated wide range of temperature changes.