VOA标准英语2009年-Going Where the Dinosaurs Roamed in th（在线收听）

Experts urge 'Westward Ho!' for finding the best dinosaur treasures

Joseph Mok | Thermopolis, Wyoming 07 December 2009

 
The Archeopteryx, a flying dinosaur about the size of a modern pigeon, is on display at the Wyoming center

The gigantic brachiosaurus, the fierce and deadly tyrannosaurus, the fast and nimble velociraptor.

Millions of years ago, long before humans existed, these creatures - and many others like them -- roamed the earth.   We visited some of the territory where dinosaurs roamed in what is now the United States.

Morrison Formation, is a group of rock layers that is prime territory for dinosaur fossils.  It is centered in the western U.S. states of Colorado and Wyoming.  We start our search for the dinosaurs of North America at the Wyoming Dinosaur Center.

Malcom Bedell is a researcher at the center.  His excavation team is digging up what he is pretty certain is a fossilized diplodocus - a large plant-eating dinosaur -- but it is slow and time-consuming work. 

 "We are still in the process of continuing to prove that this is a Diplodocus Carnegiei, basically," he explained. "We haven't found any bones that contradict that yet. Some skeletons with some types of dinosaurs come out in three weeks, some take three years and some never come out completely. This one has been ongoing for 12 years. These bones have been sitting here for more 150,000 centuries. We get one shot at it. If you fail, that's it!"

The layers upon layers of sedimentary rock can be traced back to the Late Jurassic period, about 150 million years ago, when dinosaurs ruled the earth.  The wealth of fossils buried within the rock provides scientists with important clues and data about the pre-historic environment. 

Dean Lomax is a student from England. He says if you are interested in dinosaur fossils, the American West is the place to be. "Over here there are so many more fossils to be discovered. Paleontology is a lot bigger in America than in other places. And, there are also pretty big dig sites to work out of here. The dig sites are straight up about 10 minutes away for the museum," he said.

Since it is located so close to so many fossils, it is no wonder that the Wyoming Dinosaur Center attracts people from all over the world who want to learn more about these creatures.

The displays at the Wyoming center offer many rare treasures, such as the Archeopteryx, a flying dinosaur about the size of a modern pigeon. 

 "In terms of highlights there is the Archeopteryx, which is the only one here in North America at all. It's probably the most famous fossil worldwide," Scott Hartman, science director of the center said. "Supersaurus is hard to miss. It's the 106-foot-long [35-meter-long] elephant in the room. And certainly when school kids come it's the first thing they want to look at. This specimen here is the second specimen in the world. It's named Jimbo, after the rancher's son who brought it to our attention."

To maintain the high quality of the displays, the museum's lab is hard at work seven days a week restoring the fossils.  William Wahl is a researcher at the center.  He is preparing a Camarasaurus for exhibition.  It requires a lot of preparation.  The plant-eating Camarasaurus weighed almost 20 tons.

 "This is the distal conyle  of a femur that we were working (examining) for a (much) larger Camarasaurus speciment.  What is interesting about this is that as we were prepping on this, we end up noticing there are a series of very parallel marks across the surface. Those are bite marks from whatever may be not necessarily the predators that killed this animal, but definitely something that was feeding on it," Wahl said.

The Wyoming Dinosaur Center has over 200 displays, and once the Camarasaurus bone is cleaned up and restored, it will most likely be shown to the public. 

With more than 20 full-size dinosaurs in the center's main hall, it is not surprising that 40,000 visitors a year come to the center to see these creatures who roamed the earth millions of years ago.