The biostratigraphic aspects of the lower Oligocene carbonates of the Asmari Formation, offshore, southern Iran were analyzed, providing a high-resolution dating based on recovered larger benthic foraminifera. As a part of the Tethyan Seaway, the Asmari Formation is located between the Western and Eastern Tethys Oceans. The fauna is dominated by both hyaline perforated and porcelaneous forms, including Nummulites fichteli, Operculina complanata, Eulepidina formosoides, Austrotrillina paucialveolata, and Peneroplis thomasi. Data from the Asmari Formation show a high similarity to occurrences from the Western Tethys. The co-existence of Nummulites fichteli and Eulepidina formosoides indicates SBZ 22A Subzone referring to a short time span restricted to late Rupelian.
