Early Silurian carbonate platform ostracods from Iran: A peri-Gondwanan fauna with strong Laurentian affinities

Abstract

Early Silurian (Aeronian) carbonate platform deposits of the lower Niur Formation of east central Iran yield an ostracod fauna of fourteen species dominated by podocopes with rare palaeocopes and binodicopes. The podocope-rich fauna is unusual in that Early Palaeozoic carbonate platforms are typically dominated by palaeocopes. Despite its mid-palaeolatitude peri-Gondwanan setting and isolation from low palaeolatitudes, the ostracod assemblage of the lower Niur Formation shows striking affinities to species-level with Late Ordovician and Early Silurian ostracod faunas of palaeo-equatorial Laurentia. Biogeographically the lower Niur Formation ostracod fauna also shows species- and genus-links with Late Ordovician and Early Silurian faunas of low-palaeolatitude (0°–30°S) Baltica and mid palaeolatitude peri-Gondwanan Uzbekistan, dispelling the notion of strict endemism for Early Silurian ostracods. Two new species Bulbosclerites jamshidis sp. nov. and Steusloffina fravashi sp. nov. are described.