Monday, May 22, 2017

 Hadrosaurus. DEA PICTURE LIBRARY / Getty Images

Hadrosaurus from Greek ἁδρός, hadros, meaning “bulky” or “large”, and σαῦρος, sauros, meaning “lizard”) is a valid genus of hadrosaurid dinosaur. The only known skeleton was discovered in 1858, 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. Hadrosaurus foulkii is the only species in this genus and has been the official state dinosaur of New Jersey, United States since 1991.

Reconstructed skeleton, Academy of Natural Sciences. Photo by Jim, the Photographer

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.

Hadrosaurus was named the state fossil of New Jersey, designated in 1994. It is one of the most celebrated dinosaurs ever, and is of great historic importance.

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.

The New Jersey-born Hadrosaurus is significant for more than just starting off the first wave of dinosaur-hunting fever, however. It also became, in 1868, the first dinosaur skeleton to be mounted, and then displayed, at the Academy of Natural Sciences in Philadelphia, Pennsylvania. The man responsible for that was naturalist and sculptor Benjamin Waterhouse Hawkins, who had previously created life-sized models of dinosaurs (and also some basically imaginary creatures) for the 1851 Great Exhibition in London. Hawkins based his mount of the Hadrosaurus on the work of a University of Pennsylvania paleontologist Joseph Leidy, who significantly identified Hadrosaurus as a bipedal dinosaur (previous artists had largely theorized that most dinosaurs walked on all four legs). This was certainly a step forward in our collective understanding of dinosaurs, but looking at a photo of Hawkins model, it’s still fairly inaccurate-looking to the modern eye, even if you know nothing about actual dinosaur morphology. The almost comical human-like pose, when juxtapositioned with modern artistic renderings of Hadrosaurus (or the modern mounting which was on display at the Academy in 2008) couldn’t be much farther apart. The most visible change in our understanding of the Hadrosaurus since the Hawkins mount has been that scientists no longer believe the dinosaur used its tail as support in addition to its legs, and that it probably leaned much farther forward, using its short front legs for support when necessary. That development was the painstakingly slow result of nearly 100 years of research.

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” such as 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.

However, the latest phylogeny of the Hadrosauroidea indicates Hadrosaurus is definitely placed within the monophyletic group including all nonlambeosaurine hadrosaurids. Therefore, the traditional Hadrosaurinae should be still valid for designating all non-lambeosaurine hadrosaurids.

The holotype of Hadrosaurus was found in marine sediments, which suggests the skeleton was transported by a river and then deposited in the Cretaceous sea. The Hadrosaurus remains all persist to the Woodbury Formation.

Source: www.Wikipedia.org, www.natgeo.com