Exploring Isotopes in Tree Leaves to Unravel Dinosaur Diets

In a groundbreaking senior thesis, Rio Baran, a Princeton University undergraduate from the Class of 2025, investigates the isotopic composition of modern plants to draw connections to the diets of long-extinct dinosaurs. Under the guidance of her adviser, Professor John Higgins, Baran's research utilizes isotopes found in the leaves and soil of a California redwood to explore how these chemical signatures can provide insights into ancient ecosystems and the feeding habits of prehistoric creatures.

Baran's journey began with a clandestine visit to a majestic 350-foot California redwood, where she collected samples of soil, water, and plant material. This fieldwork was made possible through the support of the High Meadows Environmental Institute and the Office of Undergraduate Research. Her aim was clear: to analyze the isotopic variations in different plant species and parts to better understand nutrient cycles within ecosystems, which in turn could illuminate aspects of dinosaur diets.

According to Professor John Higgins, who has worked closely with Baran, "Rio is an exceptional undergraduate student. She’s dedicated to all aspects of geoscience, from rocks to trees and oceans and everything in between" (Higgins, 2025). This passion has driven Baran to explore various ecological contexts, including fossils in the Australian outback and the historical coexistence of extinct species and humans through the study of ancient eggshells.

Isotopes, which are variants of chemical elements differing in neutron numbers, provide a unique window into the movement of nutrients through ecosystems. Baran's thesis, which represents the first published study analyzing both calcium and magnesium isotopes concurrently, seeks to establish correlations between modern plant isotope data and fossilized dinosaur teeth. This could ultimately help scientists answer crucial paleoecological questions about the diets and habitats of these ancient giants.

Baran's research methodology included meticulously drying and grinding plant samples, which were then analyzed using advanced mass spectrometry techniques at Princeton. Her findings revealed important distinctions in the isotopic signatures of various plant species, suggesting that calcium and magnesium isotopes can reveal significant ecological information. The results showed higher calcium isotopes in tanoak and redwoods compared to ferns and other plants, indicating a complex interplay of nutrient cycling in these ecosystems.

Baran's work emphasizes the interconnectedness of life across different eras. In her thesis, she poignantly states, "Across space, across time, across species, we are all tied together by the movement of isotopes" (Baran, 2025). This perspective not only enhances our understanding of ancient diets but also has modern implications for agriculture and environmental management.

As the research community continues to explore the relationship between isotopes and ecological systems, Baran's findings may lead to improved nutrient management practices that could inform sustainable agricultural methods. This innovative approach to understanding the past through modern science highlights the importance of interdisciplinary research and the enduring relevance of historical ecological studies in addressing contemporary challenges.

In conclusion, Rio Baran's senior thesis not only sheds light on the dietary habits of dinosaurs through isotopic analysis but also fosters a deeper appreciation for the intricate connections that bind all living organisms. As she prepares to present her findings, Baran exemplifies the spirit of inquiry and innovation that characterizes the academic pursuits at Princeton University, paving the way for future research that bridges the past and present in meaningful ways.