Dinofest International Symposium
The eastern Coastal Plains of the USA contain a Late Cretaceous dinosaur assemblage of limited taxic diversity, but with wide distribution and reasonably good abundance. The ages of specimens range from Santonian through late Maastrichtian. All Late Cretaceous eastern dinosaur specimens occur in pericontinental or marine strata, and therefore all such fossils are likely to be allochthonous. New materials and insights bear on the taphonomy of these marine occurrences, suggesting that fluvially-transported, floating carcasses, many scavenged by sharks, make up most of the eastern marine dinosaur record. There is little evidence of faunal provinciality across the entire eastern outcrop: fossil collections everywhere are dominated by hadrosaurines and immature theropods, mostly tyrannosaurids (cf. Albertosaurus) and Dryptosaurus aquilunguis. Remains of all other taxa are rare and several are known from single occurrences. Eastern hadrosaurines and tyrannosaurids appear generically similar to western taxa, implying migration by their ancestors during extreme regressions of the Interior seaway. The timing of such migrations is constrained by the presence of characteristically western clades in eastern USA by Santonian time, and by the complete absence of ceratopsians in the East. Migration must have begun or occurred during the Santonian, and must not have been possible after the middle Campanian.
Schwimmer, David R., "Late Cretaceous dinosaurs in eastern USA—A taphonomic and biogeographic model of occurrences." (1997). Faculty Bibliography. 668.