Plant-eating dinosaur a "Cretaceous weed whacker"

Plant-eating dinosaur a "Cretaceous weed whacker"

Scientists have found in southern Utah a nicely preserved skull with jaws containing 800 teeth, scaly skin impressions and other fossil remains of a new species of duck-billed dinosaur from 75 million years ago.

The bipedal herbivorous dinosaur, named Gryposaurus monumentensis, was about 30 feet long and pigged out on plenty of plants.

"What you're looking at with Gryposaurus monumentensis is basically the Cretaceous version of a weed whacker," Terry Gates, a Utah Museum of Natural History and University of Utah paleontologist, told reporters.

This is the fourth recognized species of Gryposaurus. The first was found almost a century ago. Gates said this discovery sheds light on what was going on in this part of North America about 10 million years before the dinosaurs went extinct.

Gryposaurus (pronounced grip-oh-SAWR-us) means "hook-nosed lizard," so named because of the sizable hump on the nose on the beast's large, somewhat square head.

Gryposaurus was a hadrosaur, commonly known as a duck-billed dinosaur because the wide, flattened front part of its mouth looked a bit like a duck's bill. This species was one of the larger hadrosaurs, but far from the largest. It was, however, the biggest dinosaur known from its ecosystem.

"EXQUISITE SPECIMEN"

Duck-billed dinosaurs were important plant-eaters of that time, and this one lived alongside relatives of the fearsome meat-eater Tyrannosaurus rex, herbivorous horned dinosaurs related to Triceratops and a variety of other creatures.

The scientists raved about the quality of the remains of this new species of Gryposaurus.

"As far as hadrosaur skulls in North America, this is certainly one of the most exquisite specimens we know of," said Alan Titus, a paleontologist at the Grand Staircase Escalante National Monument where the fossils were found.

This animal was on a river bed when it died, Gates said. Its mouth had about 800 teeth, helping it grind up a big buffet of plants. "You have yourself a really big eater. This guy could eat most any plant it wanted to," Gates said.

In addition to this skull, they found a second Gryposaurus with a partial skull and partial skeleton, but with the tail completely intact. Skin impressions -- only rarely fossilized -- showed the dinosaur was covered with gravelly looking scales, with some larger scales shaped a bit like a butterfly.

The environment in southern Utah was drastically different 75 million years ago than the arid place it is today. During the late Cretaceous, the last of the three periods in the age of dinosaurs, it was wet and lush, with lots of ponds, rivers and creeks. At the time, North America was split down the middle by a shallow sea.

The findings were published in the Zoological Journal of the Linnean Society.

An artist's rendering of the duck-billed dinosaur Gryposaurus monumentensis. Scientists have found in southern Utah...