New record of Durania cornupastoris (rudist) from the Campanian of the Aruma Formation, Riyadh, Saudi Arabia: Description and biogeographic remarks

A Radiolitidae (rudist, bivalvia), Durania cornupastoris (Des Moulins) is a well-known species defined as an index fossil from the Turonian (mostly middle-upper) deposits in the Mediterranean Tethys and also in the USA. This study includes new rudist materials and well-preserved samples of the species from the Campanian Khanasir Limestone Member of the Aruma Formation outcropping around the Riyadh (Saudi Arabia) region. Durania cornupastoris is characterized by the many finely ribbed, generally flat, sometimes slightly or pronounced concave posterior and ventral radial bands and bulge interband with thick costae similar to the external ornament of the rest of the right valve surface. The width of the radial bands are variable. A comparison of the species with the well-known Durania species such as Durania arnaudi (Choffat), Durania gaensis (Dacqué) and Durania apula Parona is considered. The broadening of the stratigraphic range up to the Campanian and biogeographic distribution into the eastern part of the Arabo-African plate of the species are also emphasized.