Echinoids and pectinid bivalves from the Early Miocene Mishan Formation of Iran

Abstract

Shallow marine echinoids and pectinid bivalves from the Early Miocene Guri Member of the Mishan Formation cropping out at the Gery Sheikh section north of Bandar Pohl in the area of the Hormuz Strait, Iran, are reported. The echinoid fauna indicates a Burdigalian age for the Guri Member. this is supported by new calcareous nannoplankton data from this unit, which suggest an age from Aquitanian to middle Burdigalian (NN1–NN3). From a palaeobiogeographic point of view the fauna of the Guri Member is related to the faunas from central Saudi Arabia, southeast Pakistan and northwest India. the absence of Western Tethyan elements supports earlier data suggesting that a faunal separation between proto-Mediterranean and proto-Indian ocean faunas was well developed before the terminal Tethyan Event. The echinoids Fibularia damensis Kier, 1972 and Anisaster arabica Kier, 1972 are new records for Iran, having been known before solely from Saudi Arabia. Brissus daviesi Jain, 2002 is transferred to Rhynobrissus based on the characters of its fascioles, petalodium and plas tron; this constituting the first fossil record of the genus.