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ABSTRACT: Late Cretaceous Dinosaurs of the Southeastern United States


Late Cretaceous dinosaurs of the southeastern U.S. range in age from maximum mid-Coniacian (88.5 Ma) to latest Maastrichtian (66 Ma). Known specimens are distributed in the states of Alabama (21), Georgia (6), Mississippi (10), and Tennessee (1). The main groups are: (1) hadrosaurs (Lophorothon atopus, Hadrosaurus sp., and unidentifieds); (2) tyrannosaurids (Albertosaurus sp. and unidentifieds); (3) ornithomimids (Struthiomimus (Omithomimus or Coelosaurus) antiquus and unidentifieds); and (4) nodosaurs (probably Nodosaurus). Specimens in the scientific literature are distributed among the groups as follows: hadrosaurs (19); tyrannosaurids (10); ornithomimids (4); and nodosaurs (5).

Southeastern hadrosaurs, tyrannosaurids, and ornithomimids have a first occurrence that is significantly older than related first occurrences in both the northeastern U.S. and western North American regions. These three groups may have entered the south eastern U.S. directly from western European habitats.

The hadrosaur-dominated dinosaur assemblage of the southeastern U.S. is notable for its apparent low density and diversity as compared to western North America. Southeastern U.S. dinosaurs probably inhabited a narrowly restricted zone of coastal lowlands (alluvial plains) and supratidal reaches of linear coastlines adjacent to the prominent Appalachian headland. There are three modes of preservation of dinosaurian bones: (1) shallow-marine sandy concentrates: (2) shallow-shelf sandy tempestites; and (3) shelfal marly chalk cumulates. Preservational bias is very likely, perhaps influencing an apparently high predator:prey ratio.

AAPG Search and Discovery Article #90941©1997 GCAGS 47th Annual Meeting, New Orleans, Louisiana