John Bird and Barbara Benson work on separating dinosaur bones from the surrounding rock in the CEU Prehistoric Museum. In the foreground are previously prepared specimens - stegosaurus toes and footprints. Hundreds or thousands of hours go into excavating and preparing each exhibit.
The ten-dollar word for it is "taphonomy," literally meaning the study of the grave. But we'll call it Jurassic CSI - recreating the scene of a dinosaur's death and burial that happened some 140 million years ago.
About 2,000 people got a glimpse of the first steps of the process two weeks ago at the Gooseneck dinosaur dig near Castle Dale. Now the College of Eastern Utah Prehistoric Museum is demonstrating the second phase of the investigation, which is the laboratory preparation of the allosaurus fossils. Staff and volunteers will be working on the newly-excavated bones in the museum between 2 and 5 p.m., Monday through Friday. They will answer visitor questions and explain the process.
On Tuesday, Paleontology Lab Manager John Bird and Utah Friends of Paleontology President Barbara Benson were patiently chipping away at the rock surrounding the backbones recovered from the Gooseneck site. It was pick and shovel work - dental picks, that is, with small plastic scoops to remove debris.
The rock is fairly soft, fine-grained mudstone, which is a clue for Mr. Bird about what conditions were like at the time of the dinosaur's death. "It probably was a slow-moving stream or the side of the pond," he explained. Mud won't settle in a fast moving stream, and the bones have not been rounded or scattered as they would be with fast moving water. Death probably did not occur too far away from the site where the bones scattered as they would be with fast moving water. Death probably did not occur too far away from the site where the bones were buried.
Ms. Benson, who has been volunteering for about 10 years now, demonstrated a few of the techniques she uses to tell the difference between fossil bones and rock. She tapped a piece of rock with one of her small metal tools and got a thud. Tapping bone produced a faint ringing. "Bone also has a shape and a texture that rocks don't," she explained. Still, there is a chance of making a mistake. "I have taken very good care of several rocks over the years," she quipped.
The fossils they are exposing would be the bottom side of what was exposed at the dig. Mr. Bird explained that the top of the sample was enclosed in a protective plaster cast. Then the diggers carefully excavated beneath that, inserted straps, and hauled the whole block out of the ground. This way, the bones are kept in place and protected from breakage.
Any cracked or broken bones are therefore the result of natural causes, such as geologic forces over the eons. Keeping the bones in place during the moving process makes it easier to match broken fragments and glue them together.
Mr. Bird said the backbone includes vertebrae leading from head to pelvis. The length of the spine and size of the vertebrae indicate that this creature was probably a juvenile, about the size of the allosaurus on display at the Museum of the San Rafael in Castle Dale.
Ms. Benson stressed that without volunteer effort, the excavation and recovery would have been far more difficult, if not impossible. "We are all extremely grateful for all the help we got at the site," she said. If not for a man who volunteered to drive his ATV and trailer to the rocky site, for example, it would have been necessary to hand carry the excavated block to the pickup truck for transportation to the museum.
It is not difficult to learn about excavation or preparation of fossils, she said. "All you need to know when you begin is how to listen and take directions." Both workers explained that they when they train volunteers, they often learn as much or more from their students as they teach.