Hadrosaurus, the First Identified Duck-Billed Dinosaur

Hadrosaurus. DEA PICTURE LIBRARY / Getty Images

Like many fossil discoveries from the 1800s, Hadrosaurus is simultaneously a very important and a very obscure dinosaur. It was the first near-complete dinosaur fossil ever to be discovered in North America (in 1858, in Haddonfield, New Jersey, of all places), and in 1868, the Hadrosaurus at the Philadelphia Academy of Natural Sciences was the first dinosaur skeleton ever to be displayed to the general public. Hadrosaurus has also given its name to an extremely populous family of herbivores—the hadrosaurs, or duck-billed dinosaurs. Celebrating this history, New Jersey named Hadrosaurus its official state dinosaur in 1991, and the "sturdy lizard" is frequently invoked in attempts to pump up the Garden State's paleontology pride.

What Was Hadrosaurus Really Like?

This was a robustly built dinosaur, measuring about 30 feet from head to tail and weighing anywhere from three to four tons, and it probably spent most of its time crouched on all fours, chomping on the low-lying vegetation of its late Cretaceous habitat in North America. Like other duck-billed dinosaurs, Hadrosaurus would have been capable of rearing up on its two hind legs and running away when startled by hungry tyrannosaurs, which must have been a stressful experience for any smaller dinosaurs lurking nearby! This dinosaur almost certainly lived in small herds, females laying 15 to 20 large eggs at a time in circular patterns, and the adults may even have engaged in a minimal level of parental care. (However, bear in mind that the "bill" of Hadrosaurus and other dinosaurs like it wasn't really flat and yellow, like that of a duck, but it did have a vague resemblance.)

Still, as far as duck-billed dinosaurs in general are concerned, Hadrosaurus itself occupies the far fringes of paleontology. To date, no one has discovered this dinosaur's skull; the original fossil, named by the famous American paleontologist Joseph Leidy, consists of four limbs, a pelvis, bits of the jaw, and over two dozen vertebrae. For this reason, recreations of Hadrosaurus are based on the skulls of similar genera of duck-billed dinosaurs, such as Gryposaurus. To date, Hadrosaurus appears to be the only member of its genus (the sole named species is H. foulkii), leading some paleontologists to speculate that this hadrosaur may really be a species (or specimen) of another genus of duck-billed dinosaur. 

Given all this uncertainty, it has proven rather difficult to assign Hadrosaurus to its proper place on the hadrosaur family tree. This dinosaur was once honored with its own sub-family, the Hadrosaurinae, to which better-known (and more highly ornamented) duck-billed dinosaurs like Lambeosaurus were once assigned. Today, though, Hadrosaurus occupies a single, lonely branch on evolutionary diagrams, one step removed from such familiar genera as Maiasaura, Edmontosaurus and Shantungosaurus, and today not many paleontologists reference this dinosaur in their publications.


Hadrosaurus (Greek for "sturdy lizard"); pronounced HAY-dro-SORE-us


Woodlands of North America

Historical Period:

Late Cretaceous (80-75 million years ago)

Size and Weight:

About 30 feet long and 3-4 tons



Distinguishing Characteristics:

Large size; broad, flat beak; occasional bipedal posture

mla apa chicago
Your Citation
Strauss, Bob. "Hadrosaurus, the First Identified Duck-Billed Dinosaur." ThoughtCo, Feb. 16, 2021, thoughtco.com/hadrosaurus-1092727. Strauss, Bob. (2021, February 16). Hadrosaurus, the First Identified Duck-Billed Dinosaur. Retrieved from https://www.thoughtco.com/hadrosaurus-1092727 Strauss, Bob. "Hadrosaurus, the First Identified Duck-Billed Dinosaur." ThoughtCo. https://www.thoughtco.com/hadrosaurus-1092727 (accessed June 4, 2023).