The newest dinosaur species to emerge from Grand Staircase-Escalante National Monument had some serious bite, according to researchers from the Utah Museum of Natural History (UNMH) at the University of Utah. “It was one of the most robust duck-billed dinosaurs ever,” said lead author Terry Gates. “It was a monster.”

Researchers from the Utah museum, the national monument and California’s Raymond M. Alf Museum of Palaeontology unearthed fossils of this ancient plant-eater from the rocks of the Kaiparowits Formation. Researchers announced the name of the creature – Gryposaurus monumentensis. (Gryposaurus means “hook-beaked lizard” and monumentensis honors the monument where the fossils were found.) The first description of the duck-billed dinosaur – which dates to the Late Cretaceous period 75 million years ago - appears in the Oct. 3 issue of the Zoological Journal of the Linnean Society.

Gates explained that this creature could have eaten just about any vegetation it stumbled across. “With its robust jaws, no plant stood a chance against G. monumentensis,” he said. Scott Sampson, another palaeontologist with the Utah museum who was involved with the project, emphasized the massively-built skull and skeleton, referring to the animal as the “Arnold Schwarzenegger of duck-billed dinosaurs.”

Finding the skull

In 2002, a team from the Alf Museum, were working on a stretch of the Grand Staircase that Utah researchers had not examined. Duncan Everhart, a Pennsylvania furniture maker, is credited with finding the skull. Gates and his research team later received permission from the monument to dig deeper in 2004. It wasn’t until Utah researchers began working on the skull in 2005 that the full significance of the find began to emerge, Gates said. The well-preserved skull was initially missing key pieces from the nose region. Fortunately, the California museum had collected a box full of eroded bones, including bits of the nose bone, which was critical for identifying the creature. “I knew immediately that we had some species of Gryposaurus,” Gates said.

A toothy beast

The creature’s large number of teeth embedded in the thick skull is among the features that made G. monumentensis, as well as other closely related duck-billed dinosaurs, such a successful herbivore. At any given time, the dinosaur had over 300 teeth available to slice up plant material. Inside the jaw bone, there were numerous replacement teeth waiting, meaning that at any moment, this Gryposaur may have carried more than 800 teeth. “It was capable of eating most any plant it wanted to,” Gates said. “Although much more evidence is needed before we can hypothesize on its dietary preferences.”

While the diet is unknown, given the considerable size of the creature, the massive teeth and jaws are thought to have been used to slice up large amounts of tough, fibrous plant material.

G. monumentensis is one of several new dinosaur species found in Grand Staircase, including: a Velociraptor-like carnivore named Hagryphus, a tyrannosaur, and several kinds of horned dinosaurs. In all, more than a dozen kinds of dinosaurs have been recovered from these badlands, and most represent species that are new to science. “This is a brand new and extremely important window into the world of dinosaurs,” said Sampson. “As each new find such as this new Gryposaur is made,” Titus said, ”it is placed into the greater context of an entire ecosystem that has remained lost for eons, and is only now coming under scientific scrutiny.”

Article: "A new species of Gryposaurus (Dinosauria: Hadrosauridae) from the Late Campanian Kaiparowits Formation, southern Utah, USA," Terry A. Gates and Scott D. Sampson, Zoological Journal of the Linnean Society, Vol 151, Iss 2, October 2007