This study reports the oldest robust conventional and giant magnetofossil records (~97 Ma) from marine sediments in Holland Park, Virginia, USA, bookending Oceanic Anoxic Event 2 (OAE2). Magnetic data indicates single-domain magnetite, and electron microscopy reveals various magnetofossil morphologies, including three potentially new giant magnetofossil morphologies. Abundance and morphological disparity of magnetofossils are high, but changes occur between assemblages bookending OAE2. These findings provide insights into the ecology of giant iron-biomineralizing organisms (GIBO) and suggest a wider distribution of magnetofossils in the geologic record.

Courtney L. Wagner, Ioan Lascu, Jean M. Self-Trail, Tim Gooding, Kenneth J. T. Livi, Gianna Greger, Kristina Gardner, Jody Wycech, Mark Dreier, Tom Oliver