Hadrosaurus foulkii

Dryptosaurus aquilunguis

During the late Cretaceous, North America was divided in half by a sea a thousand miles wide that stretched from the Arctic Ocean to the Gulf of Mexico.

The land on the eastern shore of this sea contained flora and fauna very different than those found to the west. Many of the plant and animal species known thus far are more primitive types. But because of subsequent uplift and erosion of the land in the eastern U.S. (such as the present-day Appalachian Mountains), terrestrial vertebrate fossils are rare.

The 30-foot long Hadrosaurus foulkii was one of the first dinosaurs discovered in North America. Its fragmentary remains were discovered in Haddonfield  New Jersey in 1858.The skull of Hadrosaurus was rugose, or roughened on the top surface, suggesting a thick calloused hump  over the nose. In life  the skin over the nasal region may have been inflatable for display purposes. 

The 20-foot long predator Dryptosaurus also roamed New Jersey 80 million years ago. Its remains are very few and fragmentary.  It was initially considered to be a Megalosaur, but it shows similarities to the African dinosaur Deltadromeus, which is considered a basal Coelurosaur, not a Carnosaur. It is possible that Dryptosaurus is in a family all its own.

If the maximum length of Dryptosaurus was only 20 feet, it was probably not a threat to adult Hadrosaurs, unless it hunted in packs. But if it was a solo hunter it could have picked off juveniles.