Geosciences undergraduate uses research tools to solve mastodon mysteries

UNIVERSITY PARK, Pa. — It took a series of events for things to fall into place. First, a mastodon had to live its life in the rolling terrain of Iowa, fossilize and be exposed by erosion in a nearby stream some 13,000 years later. Chris Widga, a vertebrate paleontologist at Penn State, had to find a home as director of the EMS Museum & Art Gallery. And Kaitlin Dasovich, a student in geosciences, had to develop a spark for undergraduate research.

Dasovich, who graduated in May, recently presented her senior thesis on work she did piecing together the life of one mastodon found by a farmer in a Wayne County stream. She used facilities in the Department of Geosciences and the Institute of Energy and the Environment to radiocarbon date the tusk, as well as measure its stable carbon and oxygen isotopes to track the temperature, climate, habitat, life cycle, diet and location of the mastodon to which the tusk belonged.

The mastodon belongs to the Prairie Trails Museum in Corydon, Iowa, and came to the University via the Office of the State Archaeologist in Iowa City, thanks to the expertise of Widga, an expert on the extinct animal of the same order as extinct North American elephants and mammoths. Widga has collaborated with Iowa scientists to better understand ice age mammals in the state for many years.

Dasovich, a native of the Philadelphia area, chose Penn State because of her interest in sustainability. As those interests grew, she found herself branching out, using laboratory tools that are equally useful in studying current and future climates as they are the past.

“I really like the part of science where we put together pieces of history,” Dasovich said. “It’s a mystery that we’re trying to solve.”

Dasovich’s research contributes to a larger mystery: What caused mastodons to go extinct? Her work just shows a glimpse of one animal, but it builds on research tracking the rise and fall of a hulking species that thrived in North America — browsing north or south to follow the warmer climate — until about 12,000 years ago. The sample is actually one of several fossilized mastodons found at the same site. Her work will help determine if these animals lived at the same time.

To solve her mystery, Dasovich tapped into Penn State’s vast resources, including state-of-the-art radiocarbon dating capabilities. This approach measures how specific molecules absorbed during an organism's life have decayed to determine its age. After the mastodon fossils were shipped from Iowa, Dasovich prepared samples. She chose a mastodon tusk because it grows just like the rings of a tree, expanding up and out as it ages. She sawed pieces of the tusk into vertical slabs before preparing them for analysis.

Widga walked Dasovich through the sample generation process. A series of steps are used to clean the tusk of any modern contaminants that were added during the fossilization process.

Dasovich’s research turned up a few key details. First, the tusk she analyzed is about the same age as another mastodon found in the same stream valley. The remains provide a glimpse of a four-year period in the life of the animal, finding that it survived on plants that preferred cooler conditions and didn’t roam far. More broadly, researchers found two mastodons in the area — a juvenile and adult — and suspect this tusk belonged to the adult.

Telling so much about an animal from its fossilized remains isn’t as hard as it seems, Widga said. The old adage, you are what you eat, rings true. Experts are able to track changes in diet throughout time using these advanced techniques.

“Mammoths will eat anything, but mastodons dined mostly on trees and shrubs,” Widga said. “These results will tell us the types of plants they were eating and give us hints of their habitat. They help us to distinguish whether a mastodon was living in swamps and bogs or forests.”

Dasovich is exploring opportunities and isn’t yet sure where her career will take her. She said she fell in love with geosciences because of the chance to work outdoors and possibly work in the realm of sustainability. Her research is broadly applicable to those areas, as well.

“These same techniques can be used to understand things like wetland and soil health,” Widga said. “They are the same tools we use to solve modern problems related to sustainability and the environment.”