Hadrosaurus

Hadrosaurus (ˌhædrəˈsɔːrəs; bulky lizard) is a genus of hadrosaurid ornithopod dinosaurs that lived in North America during the Late Cretaceous Period in what is now the Woodbury Formation about 78-80 Ma. The holotype specimen was found in fluvial marine sedimentation, meaning that the corpse of the animal was transported by a river and washed out to sea. They were large animals ranging from and . Most of the preserved elements are very robust, unusual traits in hadrosaurs. Hadrosaurus were ponderously-built animals equipped with keratinous beaks for cropping foliage and a specialized and complex dentition for food processing. Hadrosaurus foulkii, the only species in this genus, is known from a single specimen consisting of much of the skeleton and parts of the skull. The specimen was collected in 1858 from the Woodbury Formation in New Jersey, US, representing the first dinosaur species known from more than isolated teeth to be identified in North America. Using radiometric dating of bivalve shells from the same formation, the sedimentary rocks where the Hadrosaurus fossil was found have been dated at some time between 80.5 and 78.5 million years ago. In 1858, the only known specimen became the first-ever dinosaur skeleton to be mounted. In 1991, H. foulkii became the official state dinosaur of New Jersey. In 1838, John Estaugh Hopkins was digging in a marl pit (on a small tributary of the Cooper River in Haddonfield, New Jersey, and part of the Campanian-age Woodbury Formation) when he uncovered large bones. He put them on display at his home, also in Haddonfield. In 1858, the bones sparked the interest of a visitor, William Parker Foulke, who dug out the full skeleton from the marl pit in the same year. The excavation site, known as the Hadrosaurus foulkii Leidy site, is now a National Historic Landmark. Foulke contacted paleontologist Joseph Leidy, and together they recovered eight teeth from the maxillar and dentary areas, dental battery fragments, left maxilla fragments, three partial dorsal vertebrae, 13 caudal centra, including an almost complete middle caudal vertebra.