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Abstract
In the present study three species of Miogypsinoides are described from the Oligocene–Miocene Asmari Formation of the Zagros Basin in the southwest of Iran. This is the explanation of the morphological recognition and distribution of Miogypsinoides complanatus, Miogypsinoides formosensis (Upper Oligocene, Chattian) and Miogypsinoides dehaartii (Lower Miocene, Aquitanian). Nepionic acceleration is the most important factor for recognition of Miogypsinoides species. Also it is applied in stratigraphic correlation. Examination of samples indicates a decreasing number of nepionic chambers (Mx) as time passes so M. dehaartii with Mx < 10 belong to the Aquitanian age. The study of microfacies shows that these species lived in an open marine environment with normal salinity and medium hydraulic energy in a middle ramp position.
Acknowledgements
The author appreciates the help of Iran Oil Offshore Company (IOOC) and Mr Ali Ghobishavi in the field; Prof. Lukas Hottinger of the Historical Natural Museum of Basel for examining the samples, helpful suggestions and for reviewing an earlier draft of this manuscript; Dr Hossein Vaziri Moghaddam at the Esfahan University for his useful guidance and facility during the study, and Dr Paeyam Abbasi for literary editing of this draft. The author would also like to thank the reviewers for their helpful comments.