MICROSTRUCTURE OF POLYPTERID SCALES (OSTEICHTHYES: ACTINOPTERYGII: POLYPTERIDAE) FROM THE UPPER CRETACEOUS BAHARIYA FORMATION, BAHARIYA OASIS, EGYPT

Journal of Paleontology, Nov 2006 by Smith, Joshua B, Grandstaff, Barbara S, Abdel-Ghani, Medhat Said

The presence of abundant polypterid scales, and the ectopterygoid described by Schaal (1984), in the lower Bahariya Formation suggests that there were freshwater habitats proximal to the coastline during the time that the Bahariya sediments were being laid down. Previous workers have speculated that in the Cenomanian, Bahariya was located some 500 km to the north of the closest major freshwater source (Said, 1990), and there is little evidence of freshwater inputs to the Bahariya sequences at the stratigraphie level of BDP 2000-19 (K. J. Lacovara, personal commun., 2002). However, the occurrence of relatively unworn polypterid scales in the tidal inlet preserved at BDP 2000-19 argues for a freshwater input in the general area at the specifictime the inlet sediments were deposited. That this is a valid hypothesis is supported by occurrences of polypterid fossils from other sites distributed across the oasis basin (Stromer, 1936; Schaal, 1984).

ACKNOWLEDGMENTS

We thank M. Lamanna, P. Dodson, J. Poole, R. Giegengack, A. Swedan, K. Soleiman, Y. Attia. Y. Abdelrazik, K. Lacovara, J. R. Smith, J. Caton, A. Tumarkin-Deratzian, J. Losos, the Egyptian Geological Survey and Mining Authority, and the El Beshmo Lodge for invaluable assistance both in and out of the field. The authors are indebted to C. Suarez, M. Suarez, D. Terry, and D. Grandstaff for support and assistance in thin-sectioning the scales, to D. B. Dutheil for helpful discussion, and to M. Veith for SEM work. G. Arratia, W. E. Bemis, S. Novak, and A. Tumarkin-Deratzian provided valuable critical reviews of this manuscript. The Bahariya Dinosaur Project (BDP) has been supported by grants to JBS from Cosmos Studios, MPH Entertainment, the University of Pennsylvania, the Andrew W. Mellon Foundation, and the Delaware Valley Paleontological Society, and to P. Dodson (Penn) from the late E. de Hellebranth and the University of Pennsylvania. This paper is BDP contribution 6.

REFERENCES

ALDINGER, H. 1937. Permische Ganoidfische aus Ostgr�nland. Meddelelserom Gronland. 102(3):1-392.

ARAMBOURG. C. 1947. Mission Scientifique de l'Omo. 1932-33. Bulletin du Mus�um National d'Histoire Naturelle � Paris. 1(31:471-481.

BALL, J., AND H. J. L. BEADNHLL. 1903. Baharia Oasis: Its Topography and Geology. National Printing Department, Cairo, 84 p.

BARAKAT, M. A. K., H. A. HAMHD, AND M. M. KHOLIEF. 1993. Minerulogicul studies on subsurface Jurassic and Lower Cretaceous sandstones from the Western Desert. Egypt. Journal of Petroleum Geology. 16(21):213-222.

CAVIN, L., L. BOLIDAD, S. DUFFAUD, L. KAHIRI, J. Li- LOHUFF, I. ROUGET, AND H. TONG. 2001. L'�volution pal�oenvironnementale des faunes de poissons du Cr�tac� sup�rieur du bassin du Tatilalt et des r�gions avoisinantes (Sud-Est du Maroc): Implications pal�obiog�ographiques. Comptes Rendus de l'Academie de Sciences Paris, s�rie II. Sciences de la Terre et des plan�tes. 333(l()):677-683.

DAGET, J., M. GAYET. F. J. JEUNIER, AND J.-Y. SIRE. 2001. Major discoveries on the dermal skeleton of fossil and Recent polypteriformes: A review. Fish and Fisheries. 2(2): 113-124.