Earth's First Lichens Identified: Spongiophyton Dates Back 410 Million Years

A group of researchers, with support from FAPESP, has confirmed the identity of Spongiophyton as Earth's first known lichen, dating back approximately 410 million years.

Lichens are symbiotic organisms formed by fungi and algae and are considered partly responsible for structuring terrestrial ecosystems through rock dissolution and potential contributions to early soil formation.

Study Publication and Institutions

The study's findings were published as a cover story in the journal Science Advances. The extensive research involved scientists from 19 institutions, including the University of São Paulo (USP) and the Brazilian Center for Research in Energy and Materials (CNPEM).

Advanced Imaging Techniques

Lead author Bruno Becker-Kerber indicated that various light sources, including Sirius (CNPEM's synchrotron light source), along with other advanced techniques, allowed for detailed visualization of Spongiophyton's structures. The research achieved a remarkable resolution of 170 nanometers, enabling the observation of possible reproductive structures, intricate networks of hyphae (fungal filaments), and algae cells. These detailed observations are strong indicators for lichen characterization.

Chemical Analysis and Key Discoveries

Chemical analyses detected calcium, nitrogen compounds, and lipids within the specimens, crucial findings that ruled out the possibility of the organism being a plant. Co-author Jochen Brocks noted a significant nitrogen signal, which is consistent with chitin, a primary component of lichens, unlike the cellulose found in non-vascular plants. Additionally, calcium microparticles, strikingly similar to those produced by modern lichens for sun protection, were identified in the ancient fossils.

Fossil Discovery and Broader Impact

Becker-Kerber discovered the fossil in 2021 at a quarry in Rio Verde de Mato Grosso, Mato Grosso do Sul, during field research with his father, Gilmar Kerber. The material was immediately handled in a sterile manner to prevent contamination, enabling highly sensitive analyses.

The study suggests that the first lichens likely appeared in colder regions of the ancient supercontinent Gondwana. These results underscore that lichens were pioneers in transforming Earth's surface and played a vital role in the transition of life from water to land, contributing significantly to the emergence of complex ecosystems such as forests and fields.