Oct
07
2007

Giant Cretaceous lawnmower described

Gryposaurus monumentensis skull: Photo courtesy Utah Museum of Natural History
Gryposaurus monumentensis skull: Photo courtesy Utah Museum of Natural History
Scientists from Utah have described a new species of power-jawed duck-billed dinosaur in a recent issue of the Zoological Journal of the Linnean Society.

The new find, an unstoppable Mesozoic lawnmower named Gryposaurus monumentensis, was dug out of the mudstones and sandstones of the Kaiparowits Formation at the Grand Staircase-Escalante National Monument in southern Utah.

Artist rendering of Gryposaurus monumentensis: Illustration by Larry Felder
Artist rendering of Gryposaurus monumentensis: Illustration by Larry Felder
Gryposaurs were members of the dinosaur family known as Hadrosauridae, a common herbivore that lived about 75 million years ago near the end of the Cretaceous period, when the North American continent was divided in two by a large inland sea.

Four other members of the genus gryposaurus have been found prior to this, but what makes this new species different from the others is the structure of its jaw.

"The snout is very robust indeed - it is much larger and much stronger-looking than any other duck-billed dinosaur," said paleontologist Terry Gates of the Utah Museum of Natural History in Salt Lake City. "In addition, the angle of the snout is more vertical, which initially leads to a hypothesis that it had a stronger bite."

With such a powerful bite it’s no surprise to hear Gates’ UMNH colleague Scott Sampson refer to Gryposaurus monumentensis as “the Arnold Schwartzenegger of duck-billed dinosaurs.”

Grand Staircase-Escalante digsite: Workers extract Gryposaurus remains from the rock in southern Utah. Photo courtesy the Raymond M. Alf Museum of Paleontology
Grand Staircase-Escalante digsite: Workers extract Gryposaurus remains from the rock in southern Utah. Photo courtesy the Raymond M. Alf Museum of Paleontology
Remains of the new dinosaur were first discovered in 2002 by members of a dig team from Raymond M. Alf Museum of Paleontology the, based in California.

At first only the skull had been found. But soon after the lower jaw and other skeletal remains were located nearby. And the lower teeth matched perfectly with the upper skull.

With more than 300 teeth crammed into its beak and some 500 others waiting in reserve, Gryposaurus monumentensis appears to have been a giant 30-foot power mower, and must have caused the flora of the lush and humid Late Cretaceous period to quake in its roots.

"When you combine the 800 teeth with the very large, strong jaw and beak you have a very formidable plant eater," Gates said. Although the paleontologists discovered more than 20 new species of plants in the same rock unit, none of them would have probably been a match against the duck-bill’s tenacious choppers.

But the super-chomping Gryposaurus had its own worries. While it was busy decimating the Mesozoic botanicals, carnivores were busy eyeing him as their next meal.

“Here at the Utah Museum of Natural History we have examples of duck-billed dinosaur bones that have been eaten by a tyrannosaur,” Gates said.

INFO SOURCES

Story at BBC website
Story at Newscientist.com
Utah Museum of Natural History

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