In mid-July of 2013, the Deep Time exhibits team went on a fossil collecting trip to North Dakota. Our goal was to find 66 million-year- old fossils from the Late Cretaceous for our exhibits, and to learn more about paleontology. This is the third post in a series about our experiences in the field.
On our expedition, we experienced some of the difficulties of collecting a big dinosaur first-hand. It takes a lot of work to excavate, prepare, and mount a large dinosaur fossil, so scientists need to be sure that the specimen is worth all their efforts. Bigger isn’t always better, and it certainly isn’t easy!
The NMNH exhibits team excavates a dinosaur fossil from some seriously hard rock.
Photo by Kay Behrensmeyer
Scientists need research-driven reasons to collect fossils. A specimen like a T. rex should have features that are of scientific interest: perhaps it’s nearly 100% complete, or it has impressions of organs, or feathers, or maybe it has interesting injuries. If not, it may be more worthwhile to excavate a different, possibly smaller, fossil. Many large dinosaur species have already been found, while smaller organisms are more likely to be new to science. Micro- and mid-sized fossils also help scientists flesh out ancient ecosystems. Besides, small fossils can be quite complete and beautiful, like the tiny salamander jaws we found.
Big fossils aren’t worthless – for one thing, iconic specimens like Hatcher, the Triceratops, generate awe and curiosity. Any fossil, no matter the size, can increase our understanding of a species, an environment, or the fossilization process. The trick is finding the right fossil for the science you want to do – and in that case, size doesn’t always matter.
A member of the exhibits team chips away at the overburden. A Torosaurus horn had been found where’s she’s sitting.
Photo by Sally Love
Excavating a large dinosaur is arduous. It could take five years between discovering a relatively complete adult Triceratops and finally getting it out of the ground! Machines speed up the process, but they risk damaging the fossil, and don’t fit into tight quarries. The quality of the rock also affects the excavation process. Fossils in loose sandstone are relatively easy to remove, while the Torosaurus we worked on is encased in very hard siltstone, and it could take three weeks just to remove a few square meters of thin rock. Comparatively, one hour spent hunting microfossils can yield bags full of fossils representing all the major vertebrate life in the area.
Barbara Benty, Lab Director at the Marmarth Research Foundation, shows us a dinosaur skull “in progress,” in the prep lab, where it is having matrix removed to expose the fossil bones.
Photo by Siobhan Starrs
Fossil preparation takes much longer than excavation, making it more expensive. For every hour spent in the field, tack on about 6 more hours of work in the lab. Most prep labs have limited full-time paid staff, about one or two people. Left up to just one person, it could take 20 years to prepare a full Triceratops! Again, prep time varies based on the rock matrix and the fossil’s condition, but even a great fossil in very soft rock takes time.
Once the prep work is done, museums have to raise funds to pay for the mounting process. Skilled museum technicians or professional companies work with curators and exhibits staff to ensure that the mounts are anatomically accurate and visually arresting, while still protecting the individual bones. Skeletons may need to be remounted to show modern interpretations of posture, or to fit in a new space. In 2015, we’ll start remounting our iconic specimens as we begin building the new exhibition.
It’s hard to imagine, looking at a beautifully mounted skeleton in a life-like pose, just how much time, sweat, and dust went into that display. Though it’s a slow process, the possibility of finding something new and exciting is what makes fossil hunting and preparation so thrilling.
by Juliana Olsson, NMNH Office of Exhibits Writer with the support of Angela Roberts and Siobhan Starrs