- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
Oligosteginid species are distributed in all of the nine biostratigraphic zones established for the Cretaceous Bangestan group (Albian-Campanian) in the Lurestan (Luristan) province, northwest Iran. The distributional pattern is similar to that found elsewhere in the Tethys province of Europe and Asia. The rich oligosteginid faunas of the Sarvak formation (Albian-Turonian) are apparently restricted to a narrow belt separating true neritic shelf faunas from fully pelagic faunas. This suggests that oligosteginids are probably benthonic organisms which, on death, were not transported far into adjacent biotopes. The new subspecies Calcisphaerula innominata lata is included among the forms systematically described.