Hadrosaurus

Hadrpsaurus (meaning "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 80 million to 78 million years ago. 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 7 to 8 m (23 to 26 ft) and 2 to 4 t (2,000 to 4,000 kg). 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. Other fragments included a partial right coracoid, left humerus, left radius, left ulna, left ilium, right ischium, right partial pubis, the left hindlimb composed by the femur, tibia, fibula with metatarsals II and IV and the first pedal phalanx from the third digit. Foulke and Leidy studied the fossils together and, in 1858, Leidy formally described and named *Hadrosaurus foulkii* in honor of his collaborator. While originally a portmanteau of Haddonfield, the location of its discovery with the accepted suffix for dinosaurs -saurus, the name *Hadrosaurus* was scientifically justified as deriving from the Greek ἁδρός, *hadros*, meaning "bulky" or "large", and σαῦρος, *sauros*, meaning "lizard". The name was an additional play on words by Leidy since it translates from Greek as *Foulke’s big lizard*. Leidy recognized that the bones were from a dinosaur because of their similarity to those of *Iguanodon*, discovered in England some decades before but, at the time, the skeleton of *Hadrosaurus* was one of the most complete dinosaur skeletons known. Leidy's monograph *Cretaceous Reptiles of the United States*, describing *Hadrosaurus* more completely, and with illustrations, was written in 1860, but the American Civil War delayed its publication until 1865.