Principal Investigator

Lidya Tarhan attended Amherst College where she majored in Geology and English and worked on body and trace fossils and the sedimentology of Cambrian shoreline deposits, cementing her love of sandstones, exceptional fossilization and exploring the co-evolution of ecosystems and environments. She pursued her M.S. and Ph.D. at the University of California, Riverside—studying the taphonomy and paleoenvironment of the Ediacara Biota of South Australia and the evolutionary history of bioturbation, respectively. She then moved to Yale University for her postdoctoral studies, including an NSF-EAR Postdoctoral Fellowship focused on the fossilization of Earth’s earliest animal communities, before joining the faculty of the Department of Earth and Planetary Sciences as an Assistant Professor in 2019. Lidya additionally became an Assistant Curator in the Division of Invertebrate Paleontology of the Yale Peabody Museum in 2021.

Lidya Tarhan CV


Postdoctoral Scholars

Jiuyuan Wang is an Agouron Geobiology Postdoctoral Fellow. He is broadly interested in sedimentary geochemistry and geobiology, with particular focus on the co-evolution of life and environment, climate and its feedbacks on seawater chemistry, as well as the fundamental behaviors of isotope systems. He is currently working on the evolution of the carbonate factory and Si cycle in Earth’s past.





Maya LaGrange Rao is a Yale Institute for Biospheric Studies (YIBS) Donnelley Postdoctoral Research Fellow. Maya’s research focus lies at the intersection of geobiology and geochemistry; in particular, she is interested in understanding past marine conditions through trace fossils and chemical proxies recorded in sedimentary rocks. By comparing bioturbation in ancient coastal rock units to present-day coastal sediments, Maya’s work with the Tarhan Lab will investigate the response of shoreline burrowing animals to environmental change.




Olmo Miguez-Salas is a visiting Postdoctoral Associate in the Tarhan Lab. His current work focuses on examining how temperature changes and low-oxygen events affect bioturbation intensities of infauna in Long Island Sound. He is conducting experiments using environmental chambers and aquarium systems. Moreover, these experiments aim to validate the past record of similar trace fossils that are recorded in strata deposited during thermal or anoxic events.




Graduate Students

Kate Pippenger is a Ph.D. student and NSF Graduate Research Fellow. Her research centers around the many different ways that organisms interact with their environments, especially during intervals of significant environmental and evolutionary change. In particular, she is interested in tracking the effects of ecosystem engineers throughout geologic time, and is currently focused on reconstructing mid- to late-Paleozoic increases in bioturbation intensity to explore the effects of an increase in mixed layer depth. As a Ph.D. student in the Tarhan lab, she utilizes a combination of paleontological, sedimentological, and geochemical methods to answer these questions, and is also interested in projecting conclusions drawn from her deep-time research into the modern age to inform conservation and climate mitigation strategies.


Silvina Slagter is a Ph.D. student. Her research aims at understanding the interplay between major environmental changes throughout Earth’s history and the evolution and diversification of life on Earth. In particular, she seeks to identify feedbacks between biological innovations and lasting geochemical changes on Earth’s surface. Her approach to tackling these questions combines direct observation of the fossil record and geochemical archives preserved in the geologic record with laboratory experiments. She interrogates why certain minerals and modes of fossilization are restricted to time intervals associated with the appearance and radiation of animals and whether unique biological features may be recognizable through chemical and mineralogical transformations that take place during the burial and lithification of sediments.

Sydney Riemer is a Ph.D. student. She comes to Yale after completing a M.Sc. from Ben-Gurion University, where she researched the impact of bioturbation on the sulfur isotope record. She is broadly interested in understanding the mechanisms behind the coevolution of Earth’s surface environment and complex ecosystems during biological radiations/extinctions and environmental perturbations using a combination of tools from paleontology, isotope geochemistry, and sedimentology. She is also interested in exploring large datasets and integrating geochemical and paleontological data into various types of models.



Ashley Rivas is a Ph.D. student. Her interests include environmental changes and how they affect fossil abundance and diversity through the Precambrian and early Paleozoic. She is primarily interested in early radiation events and what fossil assemblages during these intervals can tell us about their ancient environments and ecologies.





Brian Beaty is a Ph.D. student, working in the Tarhan Lab for his minor discourse project on investigating potential feedbacks between bioturbation and ocean anoxia in deep time via bioturbation’s impacts on the marine phosphorus cycle. He is using the Permian-Triassic mass extinction in Svalbard as a case study. Broadly, he is interested in global Earth-system responses to major climate perturbations in deep time, including weathering on land as well as acidification and deoxygenation in the oceans, and how the geochemical composition of sedimentary rocks captures these changes in the geologic record.



Sam Shipman is a Ph.D. student doing a minor discourse project in the Tarhan Lab. He is an isotope geochemist and geochronologist currently focused on constructing age and paleoweathering frameworks for Cryogenian and Ediacaran sedimentary successions. His research in the Tarhan Lab employs stable isotope geochemistry to investigate carbonate saturation state during the Cambrian.





Maoli Vizcaíno is a micropaleontologist and paleooceanographer studying how foram and fossil foram populations are affected by oxygen minimum zones, and what assemblage work can tell us about ocean currents and dynamics in the Gulf of Mexico and Caribbean Sea both in the past, and how things will potentially change in the face of climate change. In the Tarhan Lab, for her minor discourse project, Maoli is conducting temperature and oxygen experiments on starlet anemones to ascertain how bioturbating organisms’ burrowing behavior may be affected by rising temperature and diminished oxygen levels, which are becoming increasingly prevalent in coastal waters.



James Pierce is a Ph.D. student completing his minor discourse in the Tarhan Lab. His work focuses on Earth History, including paleogeography and stratigraphy. James is studying bioturbation in the Jurassic Sundance Formation in central Wyoming. Bioturbation, the mixing of sediment at or below the sediment-water interface, is consequential to marine biogeochemistry including the oxygen and phosphorus cycles. The mixed layer constitutes the uppermost and most intensely bioturbated layer of sediment. However, it has not been well characterized in the Mesozoic, despite its importance. Understanding the effect that bioturbation had during the Jurassic will help us to understand this crucial interval that witnessed a drastic increase in biological innovation when the modern structure of benthic ecosystems was established. 

Nicolas Theunissen is a Ph.D. student working in the Tarhan Lab on his minor discourse. He is studying the impact of marine heatwaves and low-oxygen events on bioturbation intensities in Long Island Sound. He uses environmental control chambers and an aquarium system to incubate naturally occurring bioturbator communities.






Undergraduate Students

Dana Polomski is an undergraduate Earth and Planetary Sciences major on the Solid Earth track. She is in her senior year and comes to Yale after completing Math, Computer Science, and Physics associate degrees at Santa Barbara City College. She works in the Tarhan Lab on characterizing bioturbation in the mid-Mesozoic of the Sundance Seaway, and the mid-Paleozoic of the Appalachian Basin.




Tarhan Lab Alumni

Thomas Boag (currently Director of Decanal Affairs, Division of Natural Sciences, Columbia University): Tom used a combination of petrographic and geochemical methods to investigate the role of clays in fostering Ediacara-style fossilization.

Sophie Westacott (currently postdoctoral researcher at University of Bristol): Sophie investigated the silicon isotopic signature of modern radiolarians as well as the biogeochemical impact of Cambrian deep burrowing.