Frozen in time: fossil plant stem cells | Susannah Lydon

The anatomy of ancient roots pushes the boundaries of palaeobiology, pointing to more diverse root biology than previously understood

Most palaeontologists tend not to think about cells too much. Our world is dominated by the parts of living things that preserve well, and on a human scale: teeth, bones, shells, or (in my case) the bits of plants which best survive the processes of decay and preservation. Soft part preservation is highly unusual, and cell-scale detail is incredibly rare. Yet it is what soft parts do that most of biology focuses on, from molecules up to ecosystems. If we want to reconstruct lost worlds, we need to think about all these scales.

Where we do see cellular detail, it is thanks to permineralisation, a mode of preservation where mineral-rich fluids infiltrate the cells of an organism before decay can take hold. If you have seen a polished slice of petrified wood, with its tree rings clearly visible and beautifully preserved, you have seen a permineralised fossil. Microbial fossils, found in some of the oldest rocks on the planet, are the most ancient direct evidence of life on Earth, and by their very nature, show us cell-scale detail.