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Abstract: Dinosaurian Stratigraphy and Modes of Occurrence in the Southeastern Region, U.S.A.

David T. King Jr.

The outcropping Mesozoic strata of the southeastern region are limited in areal extent, and consist of Cenomanian-Maastrichtian (96-66.5 Ma) terrestrial and marine facies adjacent to the Appalachian highlands. Terrestrial facies are absent dinosaurian tracks, nests, bones, and bone beds. Marine facies contain relatively rare dinosaurian bones in two allochthonous modes of occurrence: shallow-marine concentrates and open-marine cumulates. The concentrates consist of detrial bone assemblages of multi-source fragments. They occur in clastic-dominated facies, specifically at parasequence bases, on transgressive discontinuities, and at sequence boundaries. The cumulates consist of relatively pristine bones all derived from one individual that occur in graded marl beds within s elfal hemipelagic sections.

Terrestrial facies comprise the lowest part of the section, and are separated from overlying shallow- and open-marine facies by an hiatus that encompasses the Turonian-Coniacian (92-88 Ma). This hiatus represents the 140-m, post-Turonian eustatic sea-level drop that is coeval with a major paleogeographic reconnection between western and eastern North America across the Western Interior Seaway. This paleogeographic reconnection permitted extensive migration of a new ceratopsian-hadrosaurian-tyrannosaurid fauna into eastern North America, and thus into the southeastern region.

AAPG Search and Discovery Article #90955©1995 GCAGS 45th Annual Meeting and Gulf Section SEPM, Baton Rouge, Louisiana