Hadrosaurus (Greek for "sturdy lizard"); pronounced HAY-dro-SORE-us
Habitat: Woodlands of North America
Historical Period: Late Cretaceous (80-75 million years ago)
Size and Weight: About 30 feet long and 7 tons
Diet: Plants
Distinguishing Characteristics: Large size; broad, flat beak
Hadrosaurus is simultaneously a very important and a very obscure dinosaur. It was the first near-complete dinosaur skeleton ever to be discovered in North America (in 1858, in Haddonfield, New Jersey), and it gave its name to a populous class of herbivores--the hadrosaurs, or duck-billed dinosaurs. Celebrating this history, New Jersey named Hadrosaurus its official state dinosaur in 1991.
However, as far as duck-billed dinosaurs are concerned, Hadrosaurus itself occupies the far fringes of paleontology. To date, no one has discovered this dinosaur's skull, so recreations are based on the skulls of similar genera, such as Gryposaurus. Also, Hadrosaurus appears to be the only member of its genus, prompting some paleontologists to speculate that it may really be a species (or specimen) of another genus of hadrosaur.
http://dinosaurs.about.com/od/herbivorousdinosaurs/p/Hadrosaurus.htm