TAPHONOMY OF LATE CRETACEOUS VERTEBRATE ASSEMBLAGES IN THE ATLANTIC COASTAL PLAIN OF NORTH CAROLINA, DELAWARE AND NEW JERSEY

Vertebrate fossil assemblages occur frequently in the Campanian and Maastrichtian strata of the Atlantic Coastal Plain from New Jersey southward. Numerically these fossil concentrations are dominated by chondrichthyan remains, but typically also contain osteichthyans, chelonians, crocodylians, mosasaurs, plesiosaurs and dinosaurs. More rarely, fossils of amphibians, lizards, pterosaurs, and mammals are also present. Some of these concentrations are mixed assemblages of terrestrial, estuarine, and marine forms. The taphonomy of twenty sites in North Carolina, Delaware and New Jersey was studied to determine depositional environments and possible mechanisms for mixing remains of animals inhabiting different environments.

Since Late Cretaceous vertebrate fossil concentrations are preserved in estuarine and nearshore marine sediments, usually near formational or sequence boundaries, it is probable that these fossil concentrations are the result of changes in sea level. The fossiliferous layers are probably the consequence of suitable depositional environments occurring near the sources of organic remains- in the case of the terrestrial fossils, close enough to shore to act as a taphonomic "sink' for inputs of transported or reworked bone and teeth, and for drifted carcasses. Deeper water condensed section deposits preserve a more marine fauna. Some fossil beds may be the result of storm deposition in bays. Similar mixed vertebrate faunal assemblages occur in Cenozoic parallic deposits of the eastern seaboard.