The discovery of dinosaurs fundamentally reshaped humanity’s understanding of life’s deep history on Earth. In the mid-19th century, the existence of these ancient reptiles was largely theoretical, pieced together from isolated bone and teeth fragments unearthed primarily in Europe. These scattered fossils hinted at immense creatures but did not provide a coherent picture of their anatomy. The scientific world waited for a more substantial find, which eventually emerged from a surprising location in the United States.
The Haddonfield Discovery
The first North American dinosaur skeleton was found in Haddonfield, New Jersey, in 1858. The discovery occurred in a marl pit on the farm of John Estaugh Hopkins, where workers had previously unearthed large bones. Philadelphia lawyer and amateur naturalist William Parker Foulke visited the site and directed a systematic excavation. Foulke recovered a substantial portion of a skeleton, including limb bones, pelvic fragments, and numerous vertebrae, making it the most complete dinosaur specimen recovered globally at that time. Dr. Joseph Leidy, a professor of anatomy, analyzed the find and formally presented it later that year, naming the creature Hadrosaurus foulkii—”Foulke’s bulky lizard”—in honor of Foulke.
Paleontology in North America Before 1858
Before the Haddonfield specimen, the North American dinosaur fossil record was scarce and often misidentified. Early finds included footprints in Massachusetts (1802), initially dismissed as tracks of giant birds. Fragmented bones were occasionally uncovered, such as those of the prosauropod Anchisaurus polyzelus in Connecticut (1818), but these were too incomplete to provide a clear sense of the animal. The prevailing understanding of large extinct reptiles was based on European finds like Iguanodon, which were often reconstructed in a sprawling, lizard-like posture. Even isolated dinosaur teeth identified by Dr. Leidy in 1856 were insufficient to construct a full picture of the creature.
The Significance of Hadrosaurus foulkii
The nearly complete Hadrosaurus foulkii skeleton allowed Joseph Leidy to draw revolutionary conclusions about dinosaur biology. Observing the distinct size disparity between the long, robust hind limbs and the much shorter forelimbs, Leidy deduced the creature was unlike any known reptile. He theorized the animal must have been a terrestrial, bipedal organism, a concept unprecedented in paleontology. Leidy suggested the herbivore stood habitually on its powerful hind legs, using its tail for balance, similar to a kangaroo. This idea shifted the scientific perception of dinosaurs from slow, sprawling creatures to active animals capable of upright movement.
The Legacy of the First North American Dinosaur
The discovery of Hadrosaurus foulkii had an immediate and lasting impact on science and the public imagination. In 1868, the specimen became the first dinosaur skeleton ever mounted for public display globally, at the Academy of Natural Sciences in Philadelphia. British artist Benjamin Waterhouse Hawkins created the reconstruction based on Leidy’s bipedal interpretation, making the dinosaur a global sensation. This public display spurred intense enthusiasm for fossil hunting across the continent and is considered a trigger for the “Bone Wars,” the era of fierce scientific rivalry between paleontologists Edward Drinker Cope and Othniel Charles Marsh. The species also became the namesake for a major group of duck-billed dinosaurs, the Hadrosauridae, and the original type specimen remains housed at the Academy of Natural Sciences of Drexel University in Philadelphia.