Cross-Disciplinary Science Dates Fiona’s Death

December 13, 2025

Two years ago, paleontologists discovered a fossil of a pregnant ichthyosaur in Patagonia and named her Fiona. Now, thanks to some synergistic sedimentology research, scientists know that she died 131 million years ago.  

The research was co-led by Assistant Professor Matthew Malkowski, who studies how landscapes evolve over time by analyzing sediment grains. When in the field in Chile’s Torres del Paine National Park, he crossed paths with Chilean paleontologist Judith Pardo-Pérez. They realized that the high-precision isotope dating that Malkowski was conducting on grain samples from the region could also reveal an age for the ichthyosaur.  

Researchers think that a massive underwater landslide may have killed Fiona by rapidly burying her under a layer of sediments — a demise that would explain her exquisite preservation. Malkowski’s ongoing research in Patagonia could help shed light on that theory along with the history of other marine landslides in the area hundreds of millions of years ago.