A journey on hiatus for more than 75 million years took to the skies of southern Utah on November 18, when fossil remains of prehistoric creatures were airlifted from Grand Staircase-Escalante National Monument’s remote Kaiparowits Plateau.

 

The airlift culminated this year’s paleontological field season, during which the Monument’s largest ever multiple species bone bed was discovered.

 

Dr. Alan Titus, GSENM paleontologist, said the find was made while researchers from the Utah Museum of Natural History and the University of Utah were uncovering a pristine gryposaur hadrosaur (duck-billed dinosaur) that included skin impressions and a complete skull.

 

“They found the pelvis of an animal that clearly was not a hadrosaur,” explained Titus. “Subsequent digging revealed that the pelvis belonged to an ankylosaur, an armored dinosaur resembling a tank with a club on the end of its tail. Eventually, the skull and lower jaw of this incredibly rare fossil was recovered,” said Titus.

 

“This is the first complete Late Cretaceous ankylosaur skull collected from south of South Dakota...and it is unlike anything ever before seen in North America. It more closely resembles a Mongolian species named Saichania,” said Titus.

 

According to Titus, the gryposaur-ankylosaur quarry ultimately produced three complete turtles (two with skeletons and skulls), a complete crocodile with armor and skull, a possible pterosaur (winged reptile), and a partial small hypsilophodont dinosaur. This made the site one of the single most diverse and productive ever found in the Late Cretaceous of the southern United States.

 

New discoveries on the Monument this past decade have given paleontologists a better understanding of what life was like in this region 65-80 million years ago. But the ankylosaur find could reshape theories of dinosaur migration.

 

At that time, the North American continent was split by a shallow inland sea known as the Western Interior Seaway, sometimes referred to as the Cretaceous Seaway. There was a narrow strip of land connecting the western half of what is now North America to Asia.

 

“We always thought they (dinosaurs) crossed the northern land bridge from Asia and moved toward the interior of North America before migrating south along the inland seaway into this region. Given that this species has never been found in the northern U.S. or Canada, they might have followed the California coast south, cut across the mountains at some point and then migrated north. We have a lot to learn from these discoveries, but first we have to get them back to the lab,” said Titus.

 

Before the fossils could be airlifted from the quarry, they first had to be removed from their sandstone grave and “prepared” for transit to the museum. To accomplish this task, the researchers used a gasoline-powered jackhammer and rock saw, as well as picks and shovels, to clear the rock covering the fossil. They then covered the top of the fossil with alternating layers of burlap and plaster until a “jacket” was formed. Once the top cured, the fossil was cut away from the rock base, rolled over onto its top, and the burlap/plaster process repeated on the now-exposed bottom. The prepared jacket can weigh more than half a ton.

 

“That’s why we need to use helicopters to lift the jackets out...you sure aren’t going to put ‘em in a backpack and carry them out,” joked Titus.

 

The Utah Museum of Natural History contracted with Classic Helicopter to move the cocooned fossils from the quarry to waiting trucks that would transport the jackets to labs at the museum and the Monument. By the day’s end, nine jackets were airlifted, the largest of which weighed more than 1,100 pounds.