Fossils Penetrate Mystery of Biggest Creatures : Paleontology: A dinosaur graveyard in Colorado helps paint a picture of a world 138 million years before the dawn of man.

For more than a century, scientists have been digging into a vast dinosaur graveyard in the Rocky Mountains, unraveling the mysteries of the largest creatures ever to roam the planet.

Here lie the fossilized bones of dinosaurs that lived 140 million years ago when the Front Range was a great semi-arid lowland with periods of rain and drought. Colorado was a flat landscape with large meandering streams, vegetation and open spaces.

Man was still 138 million years away.

Called the Morrison Formation for a small town southwest of Denver where the area’s first dinosaur skeleton was found in 1877, the graveyard lies on either side of the Rocky Mountains from Idaho south to New Mexico.

Paleontologists call it “the capital of dinosaur research.”

In January, a Colorado expedition found a jaw and vertebrae fragments west of Ft. Collins that belonged to the rare, meat-gulping hunter epanterias.

Robert Bakker, a University of Colorado paleontologist who led that team, said people weren’t interested in dinosaurs before the 1877 discovery because they didn’t know much about them. He said that before the Colorado find there were “miserable fragments” of fossils from Europe.

“The Morrison finds really put American science on the map and continue to surprise us every field season,” said Bakker, who has been working on the formation since 1974.

A group of preservation-minded people in Colorado has organized “Friends of Dinosaur Ridge” and is working with local and state officials on a project to protect a famous Morrison Formation outcropping southwest of Denver.

The group has proposed a park a mile long and 200 feet wide. It would lie on the first ridge--a “hogback”--west of Lakewood, Colo., a Denver suburb. If the proposal is approved, Colorado 26 would be closed from Rooney Road to Colorado 93.

Joe Tempel, environmental manager for the state highway department, described the proposed Dinosaur Ridge Park as an outdoor education laboratory, a “hands-on science, ecology, natural history park.”

The most extensive collection of Morrison dinosaur fossils is housed in the Carnegie Museum of Natural History in Pittsburgh.

“The Morrison gives us the best picture of the really big dinosaurs that lived in the age of dinosaurs,” said David Burman, curator of vertebrae fossils at the Carnegie. “Because of the nature of the environment it represented it has preserved more and better specimens of any formation in any period.”

Scientists credit the Rocky Mountains with allowing them to study the dinosaur fossils. As the Earth’s crust rose and contorted, erosion exposed layers of sandstone, limestone and shale. The layers display the fossilized bones, footprints and environment of the Jurassic Period.

The Jurassic, a time from 205 million years to 130 million years ago, is considered the second geological period in the age of dinosaurs. The Morrison Formation appeared in the Upper Jurassic period, 140 million years ago, when the dinosaurs were the largest they ever got.

The Morrison Formation is “part of one of the most complete records of the history of life you can find,” said Dr. Richard Stucky, paleontologist at the Denver Museum of Natural History. “There are episodes missing in the Rocky Mountains, but we do have a fairly complete record.”

In 1877, the dinosaur graveyard was discovered by visiting scientists who found an apatosaurus and a stegosaurus near Morrison. That find was quickly followed by the discovery of an allosaurus and a camarasaurus north of Canon City, and dozens of dinosaurs north of Laramie, Wyo. Those discoveries kicked off a kind of “fossil gold rush” that continues today.

There are dozens of theories about the mysterious mass extinction of dinosaurs at the end of the Mesozoic Era. Among them are movements of the Earth, starvation, parasites, poisons, changes in the climate, meteorites and even extraterrestrial hunters.

Bakker believes dinosaurs became extinct because of worldwide diseases that turned into an “epidemiological nightmare.”

“Dinosaurs didn’t go out with a bang, they went out with worldwide diarrhea,” he said.

Big animals travel and are very vulnerable to disease, Bakker said. As land bridges formed throughout the globe, the animals would move, spreading all the hundreds of diseases throughout all the herds on all continents--eventually killing the lot.

Most of the Carnegie collection of fossils came from what is now Dinosaur National Monument, on the northwestern Colorado-Utah border in Moffat County, Colo. Scientists took 750,000 pounds of crated dinosaurs from the quarries.

The expedition brought “the best apatosaurus, a top-notch diplodocus, a teen-age camarasaurus and the most complete sauropod,” Burman said.

The first dinosaur at the museum was the diplodocus, found at Sheep Creek, Wyo., which Burman said is one of the most famous in the world. Plaster casts have been made and shipped to Germany, France, Argentina, Spain and Portugal.

“One of the first plaster casts was shipped to the British Museum at a time when these big fossils were relatively new, so they created quite a stir in Europe,” Burman said. “Newspapers carried headlines that read ‘Dippy Comes to England.’ ”

The Morrison Formation One-hundred forty million years ago, dinosaurs roamed a landscape extremely different from that of today. When the Earth’s crust rose to form the Rocky Mountains, the dinosaur’s fossilized bones and footprints were exposed.