THE APPEARANCE OF ATLANTIC COASTAL STORMS, EVIDENCE FROM THE ELLISDALE DINOSAUR SITE, CAMPANIAN (LATE CRETACEOUS) OF NEW JERSEY

Discovered twenty-three years ago, the Ellisdale Dinosaur site of the Late Cretaceous Marshalltown Formation of New Jersey has provided new insights regarding the biodiversity of the terrestrial and freshwater faunas of eastern North America during the Campanian stage. The site has yielded dinosaurs, crocodilians and turtles, as well as exquisitely preserved and rare remains of amphibians, squamates, and mammals, including a new teiid lizard (Prototeius stageri) and batrachosauroidid salamander (Parrisia neocesariensis). Often interpreted as a transgressive lag deposit, the Ellisdale fossils occur within a fine-grained flaser-bedded estuarine facies as an anomalous layer of coarse clasts, a large percentage of the latter being disarticulated bones. The fossil component is characterized by the presence of a well-preserved “proximal” fauna of small animals (amphibians, chelonians, squamates, small crocodilians and mammals) and worn remains of a “distal” fauna (dinosaurs, large crocodilians, and large marine fish). Taphonomic, sedimentogical and stratigraphic evidence suggest an ephemeral inlet may have been opened through a regional barrier island during an ancient costal storm. As the island was flooded over, the remains of both open water marine animals and the smaller island dwellers would have been swept into the flooded backbay through storm-opened inlets, where they were mixed with the subrounded remains of animals from riverine inland environments. The eventual drop in tidal levels would have caused the bay to empty itself through the newly created inlets and channels, only to rapidly clog and refill with sediments as well as organic debris. At the Ellisdale Site, well defined growth rings are present in woody plant remains and the long bones of reptiles, suggesting seasonality. Thus, coastal storms induced by seasonal flux may have left their mark on the Cretaceous shoreline, as they still do today.