June 30 , 2016

By Rachel Sauer

Fossils, it turns out, are a bit like loose teeth: When they start wiggling, it’s time for them to come out.

So, paleontologists with the Museums of Western Colorado knew Monday that a burlap- and plaster-wrapped jacket containing about two vertebrae and parts of ribs from an apatosaurus was ready to come out because it wiggled.

Friday morning a team of museum personnel, volunteers and officials with the Bureau of Land Management gathered at the Mygatt-Moore Quarry in Rabbit Valley and carefully lifted the jacket from the spot where the bones had rested for more than 100 million years.

As a bonus, when that jacket came out, another jacket that abutted the first one started wiggling, so it came out, too. That jacket also contains some sauropod vertebrae and ribs, said Julia McHugh, the museum’s curator of paleontology. Sauropods are a group of long-necked, quadrupedal plant eaters.

The vertebrae and ribs were discovered in the mid-2000s, McHugh said, but were covered back up when paleontologists and volunteers discovered a massive sauropod femur in 2010. That 6-foot, 7-inch femur, one of the biggest finds at the quarry, was removed in June 2014. Last summer, work began again on uncovering the vertebrae and ribs.

They were in “what we call a big bone jumble,” McHugh explained. “They’re criss-crossing and lying over the top of each other, so we spend a lot of time breaking the big jumble into smaller chunks.”

A lot of that work involves undercutting the soft shale beneath the bones “until it looks like a mushroom,” McHugh said, a technique called pedestaling. It’s at that point that the jacket usually starts to wiggle. The bones are wrapped in several layers of plaster and burlap to help them safely make the trip to Dinosaur Journey in Fruita.

The bones are approximately 152 million years old, McHugh said, having laid in their bed of mudstone and shale — in the Brushy Basin member of the Morrison Formation — since the late Jurassic.

“I think everything we’re finding at Mygatt-Moore died in that area,” McHugh said. “The environment would have been marshy land with a high water table. There wasn’t a river or lake that was tumbling bones.”

After the dig season ends in August, lab work on the bones will begin. McHugh said she expects that to take up to two years, work that will include removing the rest of the rock from around the bones and piecing broken bones back together. Then, the bones will be catalogued into the museum’s database and made available for scientific research.

“Some may end up on display in our exhibit hall,” she said. “We try to rotate stuff on a regular basis.”

Once the lab work begins, visitors to Dinosaur Journey will be able to watch the process from the second-floor observation deck.

http://www.gjsentinel.com/news/articles/dinosaur-bones-journey-to-fruita-lab