Hadrosaurus

*Hadrosaurus foulkii*

* Jurassic Park Institute Artwork
* Robert F Walters Artwork

***Hadrosaurus*** (sturdy lizard) is a valid genus of hadrosaurid dinosaur. In 1858, the only known skeleton was discovered, representing the first dinosaur species known from more than isolated teeth to be identified in North America. In 1868, it became the first ever mounted dinosaur skeleton. *Hadrosaurs foulkii* is the only species in this genus and has been the official state dinosaur of New Jersey, United States since 1991.

## Description

*Hadrosaurus* lived in what is now North America, in the late Cretaceous period. It eat plants. It was likely bipedal for the purposes of running, but could use its forelegs to support itself while feeding—like all hadrosaurids, *Hadrosaurus* was herbivorous.

## Discovery

    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, putting them on display at his home, also in Haddonfield. In 1858 these bones sparked the interest of a visitor, William Parker Foulke. The skeleton was dug out from the marl pit in 1858 by Foulke. 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 an almost complete set of limbs, along with a pelvis, several part of the feet, twenty-eight vertebrae (including eighteen from the tail), eight teeth and two small parts of the jaw. Foulke and Leidy studied the fossils together, and in 1858 Leidy formally described and named *Hadrosaurus foulkii* in honor of his collaborator.

Leidy recognized that these bones were from a dinosaur by their similarity to those of *Iguanodon*, discovered in England some decades before, but the skeleton of *Hadrosaurus* was far more complete. 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.

Leidy reconstructed *Hadrosaurus* as a biped, in contrast to the view at the time that such dinosaurs were quadrupedal. The entire skeleton was completely assembled in 1868 by a team including English sculptor and naturalist Benjamin Waterhouse Hawkins and was put on display at Philadelphia Academy of Natural Sciences. The skeleton is usually kept 'behind-the-scenes' in the Academy's collections. However, from November 22, 2008 until April 19, 2009, a fully assembled cast of the skeleton and an exhibit about the science and culture surrounding the dinosaur's discovery was open to the public.

Despite the fact that the family Hadrosauridae has *Hadrosaurus* as its type genus, the skeleton lacks a skull and is too incomplete to compare to other hadrosaurines for classification purposes, leading most scientists to consider it a nomen dubium, or dubious name. When the skeleton was first assembled, it was displayed with a plaster skull sculpted by Hawkins. Many other artists have recreated *Hadrosaurus* with skulls from other, related species such as *Gryposaurus* and *Brachylophosaurus*.
A statue of *Hadrosaurus*, sculpted by Haddonfield resident John Giannotti, now stands in the center of the town of Haddonfield, commemorating its discovery there.

## Classification

Despite the fact that the family Hadrosauridae has *Hadrosaurus* as its type genus, the skeleton lacks a skull and was long viewed as too incomplete to compare to other hadrosaurs for classification purposes, leading most scientists to consider it a *nomen dubium*, or dubious name.[5] However, a re-evaluation of the fossil material in 2011 noted several distinct characteristics of the skeleton that could allow the genus *Hadrosaurus* and species *H. foulkii* to remain in use as a valid taxon.[5]

*Hadrosaurus* has also traditionally served as the basis for a large sub-family called Hadrosaurinae, which was seen as a group of largely crestless group of hadrosaurs related to the crested sub-family Lambeosaurinae. However, the changing view of *Hadrosaurus* classification in relation to other hadrosaurs has led some scientists to rename these subfamilies. In a 2008 study, Hadrosaurus was found to be more primitive than either lambeosaurines or other "hadrosaurines", and not a particularly close relative of classic "hadrosaurines" like *Edmontosaurus* and *Saurolophus*. As a result of this, the name Hadrosaurinae was restricted to *Hadrosaurus* alone, and the subfamily comprising the traditional "hadrosaurines" was renamed the Saurolophinae.

Below is a simplified cladogram recovered by Ramírez-Velasco et al. in 2012 in their description of *Huehuecanauhtlus*. This topology was recovered using an extensive sampling of sixty hadrosauroid species, and two outgroup taxa, which were scored based on 287 morphological traits,[9] and included data from two recent re-descriptions of *Hadrosaurus* by Prieto-Márquez et al. (2006) and Prieto-Márquez (2011).

## JPInstitute.com Description

Hadrosaurus was the second dinosaur named in North America and a whole family of dinosaurs - hadrosaurs - was named after it. It was the first duck-billed dinosaur found, and one of the first on the East Coast of the U.S. It was a large plant-eater and is often shown standing upright, although it actually would have spent most of its time on all four legs.

The original specimen of Hadrosaurus was found in the Cretaceous marls of New Jersey in 1858. Joseph Leidy, an anatomy professor from Philadelphia, assembled the skeleton and named it.

Hadrosaurus was large for a hadrosaur and had a typical hadrosaur body. Its skull was typical of non-crested hadrosaurs, except for a noticeable bump on the nasal bones that created a resemblance to a prizefighter with a broken nose. Hadrosaurus is sometimes erroneously used as a generic name for hadrosaurs.

## Dinosaur Field Guide Description

Hadrosaurus (sturdy lizard") was-\_in the 1860s-the first dinosaur skeleton to be exhibited in North America. Its skeleton proved the theory that some dinosaurs walked on two legs, and not on all fours, as scientists of the time had thought. This dinosaur is poorly known because, to date, no skull has ever been found for it and no new skeletons have been found. Older books may show you a head on this dinosaur, but those drawings are a guess on the part of the illustrators. At one time, scientists believed they had found the skull of Hadrosaurs, but it turned out to be the skull of another duckbill dinosaur, its closest relative, called Gryposaurus.

### Fun Facts

Hadrosaurus has its own Web site, www.levins.com/dinosaur.html

### Trivia

The only Hadrosaurs specimen on exhibit in the world is at the Academy of Natural Sciences in Philadelphia,

## Links

http://web.archive.org/web/20040214160914fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_hadro.html#