There is something cathartic about smashing rocks on a hillside, miles away from civilization, in pursuit of fossils. Each swing of the hand-pick uncovers part of a mystery. A crack forms, then deepens, and suddenly the rock splits open—to reveal a fossil or reveal nothing. A fossil is set aside. An empty rock is tossed down the hillside. The process repeats—onto the next rock.
I am one of two undergraduate researchers working under María Alejandra Gandolfo-Nixon, Plant Biology, and a team of researchers looking for fossils in Patagonia, Argentina. This is my first experience with this type of fieldwork and my first time on another continent. I am a senior, double-majoring in biological sciences and English.
Here in Patagonia, the wind is nearly constant—a far cry from my hometown in northern Colorado. The first few days at the field site we struggle through a persistent gale. Every time we turn to face it, dust assaults our eyes, our ears, and our noses. We learned to wear protective goggles, and by now our quarry is deep enough to grant us refuge.
Throughout our six-day stint at this field site, the quarry has carved steadily into the hillside. When we first arrived, there was no sign that anyone had touched the landscape. Our main quarry, containing rocks dating back to the Miocene (about five to 20 million years ago), rested under sand, eroding quietly away in the wind. No human being had ever seen or felt the rocks that we began, gradually, to pull out of the hillside. It is a strange feeling to think that we are the first people in the world to have ever seen the fossils in these rocks, and the first ones to uncover this portrait of a prehistoric world.
“We think that this place was once a lagoon,” Professor Gandolfo-Nixon tells me as we dig. I look around me to find nothing but the high desert. This place was once nothing like it is today.
The group of scientists I am working for are paleobotanists. Instead of dinosaurs (long extinct by this time), they are interested in the ancient flora at this locality. We have been able to find a lot of it. Over the course of six days, we have collected 670 fossils of various types of plant specimens.
The Treasure Hunt Is On
The first day, digging into the hillside, we uncover an upper layer with an abundance of Equisetum, or horsetails. Equisetum is an interesting ancient plant that still exists today, although it is much more abundant in the fossil record. We find mats of it at our locality. The rocks we uncover are full of Equisetum stems and nodes running in every direction. Very quickly, there is so much of it that we start to become more selective of the ones we set aside.
When we come back the next day, we start on the next layer below. Soon, we discover much more diversity. Instead of Equisetum mats, we begin to find fragments of fossil leaves. These leaves are from ancient angiosperms, or the flowering plants. Each probe promises new surprises. Some of the leaves are vague and poorly preserved, but many are so well preserved that it is possible to see the leaf venation patterns. On some, we can even make out glands.
While we are in the field, we do not attempt to identify the exact species and genus of the leaves as we uncover them. In the field, every minute counts. Our goal is to collect as many specimens as we can to bring back to the museum. Once at the museum, scientists can take the time to examine each fossil in detail and use characteristics such as leaf venation patterns to identify the family, genus, or even species of the leaf. For now, we simply dig up rocks, split them, and carefully look for the paleobotanists’ version of buried treasure.
“For now, we simply dig up rocks, split them, and carefully look for the paleobotanists’ version of buried treasure.”
Fossils—Found, Wrapped, and Packed
The leaves that we find vary dramatically in size and shape. Some are small leaves, less than an inch long. Some larger leaves are three to four inches long. We find round leaves, toothed leaves, and everything in between. From just a quick inventory, it is clear that we have uncovered several different taxa of leaves at this locality.
As we continue to dig deeper on subsequent days, we observe some patterns. For instance, we find a layer of Equisetum on the top, followed by a layer of abundant, smaller leaves, and deeper down the leaves are mostly the larger sort. Patterns like this can mean many things: Maybe the climate changed over time. Or maybe the landscape changed. The lagoon could have started to fill in with sediment, changing the types of plants that could grow here. Nonetheless, we make notes of observations like these in our field journals. They could come in handy later, when researchers begin to sort through the material we have collected.
We keep digging. It is a bit like a lottery—rocks with nothing or with fragments of a leaf or with a whole leaf, complete with well-defined venation. This never-ending game extends throughout the day, from 9:00 am to 7:00 pm or 8:00 pm. Because we are in Argentina (the Southern Hemisphere) in January, it is summer, and the sun does not set until after 10:00 pm. At the end of the long day we pack up, tired, and head back to the van. We pack the fossils by wrapping them in tissue paper to protect them. By the time we finish, it looks like we have a hundred or so Christmas presents. We joke that wrapping fossils has taught us all we need to become professional gift-wrappers.
We load up each of our packs with the fossils, the tape, the tissue paper rolls. We take with us the shovels, the hand-picks, the pickaxes. We leave the quarry uncovered as we walk back to the truck. With the truck loaded, we head back for some sleep. The next day, we wake up, eat breakfast, and return.
There is a certain personality type that is suited for fieldwork. For that type of person, fieldwork can be cheaper than therapy.