Hadrosaurus foulkii (1858): America's First Dinosaur Skeleton

Hadrosaurus foulkii was the first substantial dinosaur skeleton found in North America. It was excavated in 1858 from a marl pit in Haddonfield, New Jersey, and described that year by the Philadelphia anatomist Joseph Leidy, who realised it had walked on its hind legs. Ten years later, in 1868, it became the first dinosaur skeleton in the world to be mounted for public display.

Background: dinosaurs in the 1850s

By the 1850s scientists in Britain had named a handful of dinosaurs, including Megalosaurus and Iguanodon, but all were known only from scattered bones. Richard Owen, who coined the word “dinosaur” in 1842, pictured them as heavy, four-legged reptiles, and in that form they were sculpted for the Crystal Palace dinosaurs in London in 1854.

In the United States, finds were even more fragmentary. In 1856 Leidy had named several kinds, such as Trachodon and Troodon, from isolated teeth collected in what is now Montana. Nobody in America had yet found a large part of a single dinosaur skeleton.

The discovery at Haddonfield

Around 1838, workers digging marl on the farm of John Estaugh Hopkins in Haddonfield, New Jersey, a few miles east of Philadelphia, uncovered large bones. Marl, a crumbly clay rich in minerals, was dug from pits and spread on fields as fertiliser. The bones attracted curiosity, and many were given away to visitors and lost.

In 1858 William Parker Foulke, a lawyer and member of the Academy of Natural Sciences of Philadelphia, was spending the summer in Haddonfield and heard about the old finds. With Hopkins’s permission he organised a new excavation of the overgrown pit. Digging down through about 3 metres of marl, his workers recovered a large part of a skeleton: many vertebrae, much of both hind limbs, parts of the forelimbs and the hip, and some teeth and jaw fragments. No skull was found.

The rocks belong to the Late Cretaceous Woodbury Formation and are about 80 million years old. The animal had probably died near the coast, and its body drifted out to sea before sinking into the mud of the sea floor.

Leidy’s insight: a dinosaur on two legs

Foulke brought the bones to Joseph Leidy, the Academy’s leading anatomist. In December 1858 Leidy described them in the Academy’s Proceedings, naming the animal Hadrosaurus foulkii, “Foulke’s sturdy lizard”. He published a fuller study in 1865.

Leidy noticed that the forelimbs were much shorter than the hind limbs. He concluded that the animal had probably been able to rear up on its hind legs, perhaps in a kangaroo-like posture, supported by its tail. This was the first strong evidence that some dinosaurs were bipedal, and it challenged Owen’s picture of dinosaurs as four-legged giants. Today Hadrosaurus is understood as a member of the hadrosaurs, or duck-billed dinosaurs, which could move on two legs or on all four.

The first mounted dinosaur, 1868

In 1868 the English sculptor Benjamin Waterhouse Hawkins, who had made the Crystal Palace models, came to Philadelphia. Working under Leidy’s guidance, he assembled the Hadrosaurus bones on an iron frame in an upright, kangaroo-like pose. Missing parts, including the skull, were modelled in plaster, the head based partly on Iguanodon.

Displayed at the Academy of Natural Sciences from November 1868, it was the first mounted dinosaur skeleton anywhere. It drew such crowds that the Academy’s visitor numbers rose sharply, and the institution soon introduced an admission charge to manage them. Hawkins also made casts of the skeleton for other institutions, including the Smithsonian and Princeton.

Hawkins intended to display Hadrosaurus in a “Paleozoic Museum” planned for Central Park in New York. The project collapsed in 1871 amid the politics of the Tammany Hall era, and his unfinished models were smashed and buried.

Later history and legacy

Hadrosaurus became the namesake of the whole hadrosaur family, one of the most common groups of plant-eating dinosaurs of the Late Cretaceous in North America and Asia. Because the original specimen lacks a skull, its exact relationships within the family are still debated.

New Jersey remained important in early American palaeontology. In 1866 Cope described a large meat-eating dinosaur, now called Dryptosaurus, from another marl pit in the state. Cope’s later fierce competition with Othniel Charles Marsh became known as the Bone Wars.

Hadrosaurus was named the official state dinosaur of New Jersey in 1991, and the discovery site in Haddonfield was declared a National Historic Landmark in 1994. In 2003 a life-size bronze statue of Hadrosaurus was unveiled in the centre of Haddonfield. The original bones are kept by the Academy of Natural Sciences of Drexel University in Philadelphia.

What Hadrosaurus was like

Hadrosaurus was a large plant-eater, probably around 7 to 8 metres long and weighing a few tonnes, although estimates are uncertain because so much of the skeleton is missing. Like other hadrosaurs, it probably had a broad, toothless beak and hundreds of tightly packed teeth arranged in “dental batteries” that ground tough plant material. Worn teeth were constantly replaced from below.

It lived along the coast of Appalachia, the eastern landmass of North America in the Late Cretaceous, when a shallow inland sea divided the continent in two. New Jersey then lay close to the Atlantic shoreline, and many of the state’s dinosaur remains are found in marine sediments, washed out to sea after death alongside fossils of sharks, turtles and mosasaurs.

Because Hadrosaurus is known from only one partial skeleton, scientists cannot say for certain whether it had a crest on its head, as some later relatives did. Its broad hips and long legs suggest it could walk comfortably on two legs and drop onto all fours to feed.

Myths and facts

• “Hadrosaurus was the first dinosaur found in America”: earlier finds of teeth and bones existed, including fossil footprints in the Connecticut Valley and teeth from Montana. Hadrosaurus was the first reasonably complete skeleton.
• “The 1868 mount was accurate”: it was a bold step for its time, but the kangaroo-like pose, with the tail dragging on the ground, is now considered wrong. Hadrosaurs held their tails roughly level.
• “The skull was found”: no skull was ever recovered. The head on the 1868 mount was a plaster model.

Key people

• William Parker Foulke (1816–1865): lawyer and naturalist who organised the 1858 excavation.
• Joseph Leidy (1823–1891): anatomist who described Hadrosaurus and proposed its two-legged posture.
• Benjamin Waterhouse Hawkins (1807–1894): sculptor who mounted the skeleton in 1868.
• Edward Drinker Cope (1840–1897): Academy palaeontologist who described other New Jersey dinosaurs and later fought the Bone Wars.

Timeline

• c. 1838: Workers find large bones in a marl pit on John Estaugh Hopkins’s farm in Haddonfield.
• 1858, summer: William Parker Foulke excavates the pit and recovers much of a skeleton.
• 1858, December: Joseph Leidy names Hadrosaurus foulkii.
• 1865: Leidy publishes his detailed study of Cretaceous reptiles.
• 1868, November: The mounted skeleton goes on display in Philadelphia.
• 1991: Hadrosaurus becomes New Jersey’s state dinosaur.
• 1994: The Haddonfield discovery site becomes a National Historic Landmark.
• 2003: A bronze statue of Hadrosaurus is unveiled in Haddonfield.

Why it matters

Hadrosaurus changed how scientists and the public imagined dinosaurs. It showed that some walked on two legs, and as the world’s first mounted dinosaur skeleton it began the tradition of great dinosaur displays that still draws millions of visitors to museums every year.