When magnetotactic bacteria (MTB) die their magnetic particles can be preserved in sediments as magnetofossils. The magnetic properties of magnetofossils makes them easily identifiable in bulk sediments using magnetic measurements. Magnetofossils are exciting biomarkers for these reasons and because they can record life in sediments which biological remains are not always preserved. Although I study living MTB, a much larger part of my research program involves magnetofossils from past global warming events. I use a combination of scanning electron microscopy, transmission electron microscopy, and rock magnetic measurements to determine and characterize changes in MTB assemblages during these time periods. My work is made stronger by collaboration with experts in micromagnetic modeling, statistics, and benthic foraminfera. This work allows me to better understand changes in marine oxygen and nutrient supply during periods of rapid planetary change.


Wagner, C. L., Stassen, P., Thomas, E., Lippert, P. C., & Lascu, I. (2022). Magnetofossils and benthic foraminifera record changes in food supply and deoxygenation of the coastal marine seafloor during the Paleocene-Eocene Thermal Maximum. Paleoceanography and Paleoclimatology, 37, e2022PA004502.

Wagner, C. L.., Lascu, I., Lippert, P. C., Egli, R., Livi, K. J. T., & Sears, H. B. (2021). Diversification of iron-biomineralizing organisms during the Paleocene-Eocene Thermal Maximum: Evidence from quantitative unmixing of magnetic signatures of conventional and giant magnetofossils. Paleoceanography and Paleoclimatology, 36, 1-25 e2021PA004225.

Here’s a write-up that summarizes our findings:

Wagner, C. L., R. Egli, I. Lascu, P.C. Lippert, K. Livi, H.Sears. (2021). In situ identification of   giant, needle-shaped magnetofossils in Paleocene-Eocene Thermal Maximum sediments. Proceedings for the National Academy of Sciences.

If you are not keen on reading the paper, here are a couple write-ups that summarize our findings:

Please feel free

to reach out!

Contact information:

Courtney Wagner, Ph.D.

Peter Buck Postdoctoral Fellow

Smithsonian Institution, NMNH

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