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GREEN RIVER - As Jim Kirkland picks his way across the barren mesa top, the tantalizing dinosaur bones peeking out from the gray mudstone are only part of what excites the state paleontologist about this newly opened site.
The importance of the location, found last year and opened for initial work last week, lies in when these massive creatures roamed. Kirkland believes this stretch of rugged badland could be from a time that is now a gaping hole,
125 to 148 million years ago, in paleontology's understanding of ancient North American life.
"It's just amazing how many bones are in this area," Kirkland said as he wandered Tuesday through the several-acre-site known as Don's Ridge.
If geologists and other researchers help Kirkland confirm the date of this site, all the species fossilized within would be new to science.
In a state bursting with active dinosaur digs - including the home of vegetarian-carnivore hybrid Falcarius utahensis a few ridges away - this quarry could offer a glimpse into land life of the early Cretaceous not found anywhere else on the continent.
It remains unclear when this area may fit into the 23-million-year-old gap in North America's record. Worldwide, the only comparable window into this era comes from southern England, Kirkland said.
"Everything should be new," if the Green River site is the age they believe, he said.
An advance crew of four people spent 10 days at the site before closing it Wednesday until work resumes this summer. Some of the initially discovered bones appear to be relatives of Gastonia, an 11-foot-long plant muncher.
"So far, the armored dinosaur is twice as big as Gastonia," Kirkland said.
Other new bones may come from a type of Iguanodon, a vegetarian dinosaur that could grow to more than 30 feet long. The Bureau of Land Management property southwest of Green River includes some whole bones but many broken ones. Both types could help explain the area's story.
"You can have a mixed bag of history for the bones," he said, "so there's stuff that died 50 years earlier and was broken up and then stuff that died a week before it was buried that is in good shape."
Kirkland said during the early Cretaceous, this region was likely dry and supported primitive conifers, cycads and ferns. Don's Ridge, named for Utah Geological Survey researcher Don DeBlieux who found the site, may have been a muddy river valley. Sediments would bury and preserve creatures that died close to the waterway.
Finds from the nearby Crystal Geyser quarry, the Falcarius site, encouraged DeBlieux and others to examine similar levels of what is known as the Cedar Mountain rock formation.
"We've been systematically trying to prospect the Crystal Geyser interval," he said of geological formations of similar age found at different locations.
Last September, DeBlieux began finding evidence of bone along a ridge. Further investigation revealed several bone-bearing sites in the same rock formation.
"It goes all the way around the hill," Kirkland said, "it's a gigantic site."
A several-foot-long Iguanodon thigh bone is among the earliest material being covered in plaster for safe transport to Salt Lake City. Wielding hammers and chisels, two team members clanked away to sever the last rock tendons holding the thigh bone in place.
"Once we get further into the hill, we're going to see some really great stuff," said Jennifer Cavin, a Utah Geological Survey researcher, as she scooped material from an opening in the thigh bone's plaster jacket to lighten the load.
While the crew, which included Dinosaur National Monument's Scott Madsen, removed some bone in the 10-day opening session, much of the later work centered on preparing a grid system for the sprawling site.
Cavin said later crews will note the location of each bone found in relation to other finds. Such information could determine whether the bones accumulated here as part of a pattern or in a random manner.
The potential of this site has sparked Kirkland's imagination, but he must now convey that excitement to groups that control paleontological funding. With proper funding, the work could take five years. A tight budget could require twice as long working the site.
Limited time and financial resources already prompted Kirkland to turn over another site near the Crystal Geyser quarry to the College of Eastern Utah. For this summer, Kirkland and Cavin will oversee the Crystal Geyser site while DeBlieux runs Don's Ridge.
Kirkland hopes the rocky terrain of the state's newest quarry surrenders enough of its secrets to piece together the site's importance in the coming years.