A biostratigraphic study was carried out in the Lower Creaceous (Aptian-lower Albian) Zagros basin, northeastern Shiraz located at southwestern Iran, allowing the recognition of one lithostratigraphic unit. The Lower Cretaceous shallow-water limestones on the northeast of Shiraz contains abundant and diversified orbitolinid foraminifera. A biostratigraphy, based on the orbitolinid taxa and their distribution, is proposed for the Aptian and Albian deposits in the Lower Creaceous (Aptian-lower Albian) Zagros basin, northeastern Shiraz located at southwestern Iran, allowing the recognition of one lithostratigraphic unit. Three orbitolinid biozones have been recognized: 1) Palorbitolina lenticularis Assemblage Zone in the Lower Aptian; 2) Mesorbitolina parva Total Range Zone in the Late Aptian; 3) Orbitolina (Mesorbitolina) texana Assemblage Zone in the uppermost Aptian-lower Albian, the body of strata being characterized by a distinctive assemblage of Orbitolina (Mesorbitolina) texana and O. (M.) parva. The following taxa are the most abundant: Mesorbitolina texana, Mesorbitolina parva, Orbitolina sp., Pseudocyclammina lituus, Pseudochrysalidina conica, Pseudochrysalidina cf. arabica, Pseudocyclammina hedbergi, Praechrysalidina infracretacea, Cuneolina pavonia, Dictyocunus arabicus, Iraqia simplex, Vercosella laurentii, Protomarssonella trochus, Nautiloculina oolithica, and calcareous algae such as Salpingoporella dinarica, Trinocladus tripolitanus, Terquemella sp. and Lithocodium aggregatum-Bacinella irregularis.
 A. Arnaud-Vanneau, “Larger Benthic Foraminifera,” In: P.-C. De Graciansky, J. Hardenbol, T. Jacquin and P. R. Vail, Eds., Mesozoic and Cenozoic Sequence Stratigraphy of European Basins, Special Publication, Society of Economic Paleontologists and Mineralogists, Tulsa, 1998, pp. 721-733. books.google.com/books?isbn=1862393060?
 R. Schroeder, F. S. P. Van Buchem, A. Cherchi, D. Baghbani, B. Vincent, A. Immenhauser and B. Granier, “Revised Orbitolinid Biostratigraphic Zonation for the Barremian—Aptian of the Eastern Arabian Plate and Implications for Regional Stratigraphic Correlations,” Geo-Arabia Special Publication 4, Vol. 1, 2010, pp. 49-96.
 J.-P. Masse, “The Lower Cretaceous Mesogean Benthic Ecosystems: Palaeoecologic Aspects and Palaeobiogeographic Implications,” Palaeogeography, Palaeoclimatology, Palaeoecology, Vol. 91, 1992, pp. 331-345.
 H. Afsharharb, “Petroleum Geology of Iran,” Engineering Faculty of Tehran University, Tehran, 2001.
 H. Motiei, “Stratigraphy of Zagros: Treatise of Geology of Iran,” Natural Iranian Oil Company, Tehran, 1993.
 G. A. James and J. G. Wynd, “Stratigraphic Nomenclature of Iranian Oil Consortium Agreement Area,” American Association of Petroleum Geologists Bulletin, Vol. 49, No. 12, 1965, pp. 2192-2245.
 A. Gollestaneh, “An Introduction to the Stratigraphic Distribution of Fossil Calcareous Algae in Southern Iran,” Iranian Oil Operating Companies, Geological and Exploration Division, Tehran, 1966.
 A. Kheradpir, “Stratigraphy of the Khami Group in Southwest Iran,” IOSC (NIOC), Tehran, 1975.
 M. Ghavidel Syooki, “Palynological Environmental Age Determination of Dariyan Formation,” NIOC, Exploration and Technology Division, Tehran, 1979.
 A. Kalantari, “Microbiostratigraphy of Sarvestan Area, Southwestern Iran,” National Iranian Oil Company, Tehran, 1986.
 M. P. N. Shirazi, “Calcareous Algae from the Cretaceous of Zagros Mountains (SW Iran),” World Applied Sciences Journal, Vol. 4, No. 6, 2008, pp. 803-807.
 M. P. N. Shirazi, “Albian-Cenomanian Zonation (Foraminifers and Calcareous Algae) in the Northern Fars, Iran,” American Journal of Applied Sciences, Vol. 6, No. 4, 2009, pp. 709-714.
 M. Berberian and G. C. P. King, “Towards a Paleogeography and Tectonic Evolution of Iran,” Canadian Journal of Earth Science, Vol. 18, No. 2, 1981, pp. 210-265.
DOI: 10. 1139/e81-019
 M. Alavi, “Tectonics of the Zagros Orogenic Belt of Iran: New Data Interpretations,” Tectonophysics, Vol. 229, No. 3-4, 1994, pp. 211-238.
 J. Golonka, “Cambrian-Neogene Plate Tectonic Maps,” Institute of Geological Sciences, Jagiellonian University, Kraków, 2000. ww.dinodata.info/ Golonka/phan.pdf
 A. R. Loeblich Jr. and H. Tappan, “Foraminifera Genera and Their Classification,” Van Nostrand Reinhold, New York, 1988.
 R. Delloffre, “Nouvelle Taxonomic des Algues Dasycladales (New Taxonomy of Dasycladale Algae),” Bulletin des Centre de Recherches Exploration-Production Elf-Aquitaine, Vol. 12, No. 1, 1988, pp. 165-217.
 J. P. Bassoullet, P. Bernier, M. A. Conrad, R. Deloffre and M. Jafrezo, “Les Algues Dasycladales du Jurassique et du Cretace,” Geobios Memoire Special, Vol. 2, No. 8, 1978, pp. 259-290.
 R. J. Dunham, “Classification of Carbonate Rocks according to Depositional Texture,” American Association of Petroleum Geologists Bulletin, Vol. 43, No. 1, 1962, pp. 108-121.
 J. L. Wilson, “Carbonate Facies in Geologic History,” Springer-Verlag, New York, 1975.
 E. Flügel, “Microfacies of Carbonate Rocks: Analysis, Interpretation and Application,” Springer-Verlag, BerlinHeidelberg, 2004.
 M. Sampo, “Microfacies and Microfossils of the Zagros Area, SW Iran (from the Permian to Miocene),” International Sedimentary Petrographical Series, Vol. 12. No. 1, 1969, p. 102.
 I. Veli? and B. Soka?, “Biostratigraphic Analysis of the Jurassic and Lower Cretaceous in the Wider Region of Ogulin, Central Croatia,” Geolo?ki Vjesnik, Vol. 30, No. 1, 1978, pp. 309-337.
 I. Veli? and J. Tisljar, “Biostratigraphic and Sedimentologic Characteristics of the Lower Cretaceous Deposits of the Veli Brijun Island and Comparison with the Corresponding Deposits in SW Istria (Western Croatia, Yugoslavia),” Geolo?ki Vjesnik, Vol. 40, No. 1, 1987, pp. 149-168.