ALDER, MONTANA – I drive slowly over the hilly terrain in Fossil Basin and park near the remnants of an old campsite. In the 1950s and early 1960s, botanist Herman Becker camped here and collected fossil insects and plants from the Renova Formation’s paper shales.
We are the first, since Becker, to explore this fossil bed. Our work begins where his left off.
Most of the fossil-rich shale is found on private land, and we were lucky to get permission from the landowner to excavate here. We are working to pinpoint which shale horizons yield each fossil type. To do that, we need to remove all the overburden that covers the rock layers at our excavation sites. It’s a slow process, as the overburden must be thoroughly screened for fossils.
After a few hours, I stare at the many specimens the team has uncovered. Some are as thin as paper; others are more than an inch thick. The thinnest can flex with the slightest change in temperature or humidity. To help preserve them, I carefully glue each fossil to a piece of polycarbonate sheeting with water-soluble paste.
Later at camp, Sam Heads and I give each specimen a field identification number, which he records in his field notebook. I wrap the fossil-laden polycarbonate sheets in bubble wrap, and arrange the packets in plastic crates. This will protect the fossils during our long ride back to Illinois.
It has been an extremely successful year. Our first day of collecting yielded more fossils than last year’s entire two-week expedition. We are returning to the Illinois Natural History Survey with almost a thousand specimens. Each will be assigned a permanent collection number (different from the field number). Each will be photographed and glued to its own polycarbonate sheet. I’ll repair any broken fossils with non-water-soluble glue. The specimens will be organized taxonomically in cabinets and their accompanying data uploaded to a public database.
Each fossil we’ve collected — this year and last — adds a piece to this area’s ancient puzzle. Someday we hope to see the complete picture.