June 16, 2008

Major Dinosaur Fossil Find in Southern Utah

A team of Illinois scientists looking for fossils of big dinosaurs in Utah's Morrison limestone struck pay dirt last month, opening the possibility of a major dinosaur quarry outside Hanksville.

In recent weeks, the group, representing the Burpee Museum of Natural History, uncovered "a logjam" of 148-million-year remains of as many as six dinosaur species and massive coniferous trees so well preserved you can feel their bark and read their tree rings.

And that's just scratching the surface, said paleontologist Matt Bonnan, an associate professor of biological sciences at Western Illinois University. Scientists are confident the find could rival Utah's famous Cleveland-Lloyd Dinosaur Quarry and Dinosaur National Monument in terms of expanding our biological understanding of the late Jurassic period.

"What's exciting is that it's the first time in a long time where we have logjams of bones of a different species in one place," said Bonnan. The Burpee tapped Bonnan for the Hanksville digs because of his expertise in sauropods, the dinosaur family whose members were the largest animals to ever walk on land. The museum, in the Chicago suburb of Rockford, is building a new exhibition hall and its Utah expeditions are intended to find specimens to fill it, according to Utah state paleontologist Jim Kirkland.

"We're thrilled to have someone working this site," Kirkland said. "Now that there is a serious long-term research effort, it has the potential to be an economic asset to Hanksville."

The area has been known as a source of fossils to locals and land managers for years, but it was only in the last few weeks that its potential impact to science became known, said Bureau of Land Management paleontologist Scott Foss. A geologist in the BLM's Hanksville office directed the Illinois team to the spot last summer when the Burpee group arrived looking for bones.

Souvenir hunters and rockhounds have picked over the spot, but the damage never extended beneath the surface. BLM plans to close the area to public access to protect the fossil resource and perform an environmental review.

The Morrison formation is the most fertile ground for dinosaur prospecting in North America, yielding some of the best specimens of brand-name dinosaurs, including Utah's signature fossil, allosaurus. Accordingly, the Burpee group is discovering specimens already familiar to science and school children: allosaurus, stegosaurus, apatosaurus, camarasaurus, brachiosaurus, and diplodocus. The last four are sauropods, massive planteaters that grew to 60 to 90 feet in length and are easily recognized by their long necks and tiny heads. The only complete brachiosaurus specimens have been recovered in Africa, so the Hanksville specimen could present a rare opportunity to compare how the same dinosaur evolved on different continents, Bonnan said.

These species, which lived in the late Jurassic period, are among the most well-studied dinosaurs, unlike the younger Cretaceous-period specimens the University of Utah is recovering from nearby Grand Staircase-Escalante National Monument. While Utah scientists are preoccupied with identifying previously unknown dinosaur species, the Illinois team is interested in deepening our understanding of well-known species and the world they inhabited.

"We will be able to take a look at old bones with new eyes and new techniques," Bonnan said. "In the old days they looked for the best specimens for display. What we tend to be interested in nowadays when you have a log jam is what it can tell you about the flow of the river system and about the ancient environment."

Last month, scientists found countless bones strung along a half-mile area believed to have been a sand bar where an ancient river deposited dismembered dinosaurs and trees. Some of the bones are articulated, but most are scattered and it could take years to excavate and assemble complete specimens.