Members of the Departments of Paleobiology, Exhibits and Education and Outreach traveled to North Dakota and Montana this past July as part of our preparations for the Last American Dinosaurs exhibition. We had visited the same area the previous summer to collect fossils of plants and animals that lived during the Cretaceous Period, shortly before the asteroid impact 66 million years ago that wiped out many plant and animal species, including dinosaurs. This time, we expanded our search to include the fossils of species that survived the catastrophe and thrived during the years that followed, in the early part of the Paleogene Period.
Our first order of business was to collect the fossils of small animals, so we spent a lot of time searching the ground at sites where the sediments are rich in small bones, teeth and other "microvertebrate" fossils. The tiny fossils become visible on the surface as the sediment erodes away, but finding them requires sharp eyes, concentration, and a lot of stooping and crawling to see exposed rock surfaces up close. We also collected bulk sediment at one of the sites -- material that volunteers in FossiLab, the fossil preparation lab anchoring the Last American Dinosaurs exhibit, will examine carefully under microscopes in search of more and smaller fossils. Before we packed the bulk sediment for shipping to the Museum, we ran it through sieves made from screens that were coarse enough to let fine grains of sand and clay pass through, but fine enough to retain the smallest fossils. Concentrating the fossils in this way means easier fossil hunting in the lab, and fewer heavy buckets to ship.
We also collected several larger fossils for educational programming in the exhibit. The excavation of a turtle specimen is shown in the photo series below.
We visited many other sites during our time in the field, and we collected enough sediment and specimens in field jackets to fill a large shipping crate. Typical of such short trips, our goal was to collect as much material and information as possible, leaving the delicate work of fossil cleaning, stabilization, and identification to be done in FossiLab and our behind-the-scenes preparation lab. The fossils found this season will be keeping our volunteers and staff busy for many months to come.
The Last American Dinosaurs Exhibition will open on November 25th.
Photos by Abby Telfer unless labeled otherwise.