LATE CRETACEOUS DINOSAURS FROM NEW JERSEY AND DELAWARE: STRATIGRAPHY, TAPHONOMY AND DEPOSITIONAL ENVIRONMENTS

Campanian and Maastrichtian dinosaur remains from the Middle Atlantic states are found in estuarine and near-shore marine deposits, and occur in several taphonomic modes: 1).isolated bones and teeth in bonebed concentrations; 2). single finds of several associated bones; 3). single partial skeletons. A half dozen stratigraphic units have consistently yielded dinosaurs. The Woodbury Formation is the source of Hadrosaurus foulkii, found in 1858 and still the most complete dinosaur skeleton from New Jersey. This unit also produced Ornithotarsus immanis, the lower leg bones from a larger hadrosaur. Stable strontium isotope stratigraphy has yielded an age estimate of between 78.5 and 80.5 ma for the Woodbury Formation shell bed that produced H. foulkii.

The Englishtown and Marshalltown Formations of mid-Campanian age have produced juvenile hadrosaur teeth, larger hadrosaur bones, and theropod bones and teeth, some possibly of a dromaeosaur. The late Campanian Wenonah and Mount Laurel Formations have been a consistent source of isolated hadrosaur bones and teeth, a few nodosaur bones, and theropod bones including the paratype material of Coelosaurus antiquus.

On the basis of new ammonite biozonation data, the Navesink and New Egypt Formations yield the last (youngest) dinosaur remains in the area, the late Maastrichtian partial skeletons of Dryptosaurus aquilunguis and H. minor. A possible lambeosaurine is also from this level. Concentrations of dinosaur and other vertebrate remains in New Jersey and Delaware accumulated in response to sea level cycles and tend to be close to sequence boundaries in shallow marine or estuarine deposits.