A revision of the upper part of the Saq Formation and Hanadir Shale (lower Ordovician) of Saudi Arabia

Abstract The previously termed Hanadir Shale of Saudi Arabia is described and re-defined as the Hanadir Formation. At the type locality of Al Hanadir the unit is probably entirely of Llanvirn age while further north shelly faunas of possible Llandeilo age occur in the upper part. Trace fossil assemblages with abundant cruzianids (C. furcifera, C. rugosa, C. goldfussi),Pelecypodichnus, DidymaulichnusandDiplichnitesindicate an Arenig age for beds in the upper part of the underlying Saq Formation, while the top of this unit yielded hitherto unrecorded pendent and biserial scandent graptolites, a sparse shelly fauna of lingulacean brachiopods,Neseuretussp. and the trace fossilsCruziana? imbricataandPhycodes.