Acta Geologica Polonica, Vol. 50 (2000), No. 1, pp. 175-190 Maastrichtian (Late Cretaceous) ammonites from the Owl Creek Formation in northeastern Mississippi, U. S. A . W. JAMES KENNEDY1 & WILLIAM A. COBBAN2 1 Geological Collections, Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, U.K. E-mail:
[email protected] 2 70 Estes Street, Lakewood, Colorado 80226, U.S.A. ABSTRACT: KENNEDY, W.J. & COBBAN, W.A. 1999. Maastrichtian (Late Cretaceous) ammonites from the Owl Creek Formation in northeastern Mississippi, U.S.A. Acta Geologica Polonica, 50 (1), 175-190. Warszawa. Ammonites are locally abundant in the Owl Creek Formation in northeastern Mississippi. The assemblage is dominated numerically by Eubaculites carinatus (MORTON, 1834), a widely distributed marker fossil for the Maastrichtian that also occurs in South America, southern Africa, Madagascar, western Australia, southern India, and western Europe. It is accompanied by Sphenodiscus pleurisepta (CONRAD, 1857), Baculites cf. B. claviformis STEPHENSON, 1941, B. cf. B. undatus STEPHENSON, 1941, Discoscaphites iris (CONRAD, 1858), D. sphaeroidalis sp. nov., and D. cf. D. conradi (MORTON, 1834). Key words: Cretaceous, Maastrichtian, Ammonites, U.S.A., Mississipi. INTRODUCTION County, Mississippi (Text-fig. 1, locality 12; HILGARD 1860). Details of the locality were given by The Owl Creek Formation is the youngest unit of SOHL (1960, p. 39), who measured 4.9 m of calcare- the Cretaceous sequence throughout its outcrop in ous, argillaceous, micaceous, slightly glauconitic northern Mississippi; it is bounded unconformably sand containing a rich fauna in which original arag- below by the Ripley Formation (Campanian and onitic shells are preserved.