A new international study identified a fossil found in Brazil as one of the oldest lichens in Earth’s history, revealing that these organisms were already common more than 410 million years ago. The discovery helps explain how life managed to thrive on land.
The investigation, published in the journal Science Advances and led by Bruno Becker-Kerber, a researcher at Harvard University, analyzed a Devonian-period fossil known as Spongiophyton (dated between 419 and 359 million years ago). Using cutting-edge X-ray imaging techniques and other modern methods, the scientists were able to observe a combination of fungi and algae similar to that of modern lichens.
“Our findings show that lichens were not marginal organisms, but fundamental pioneers in transforming the Earth’s surface,” explains Becker-Kerber. “They were the ones who helped create the soil that allowed plants and animals to establish themselves and diversify on land,” he adds.
The results indicate that the first lichens evolved in the cold polar regions of the supercontinent Gondwana, corresponding to what is today South America and Africa.
Professor Jochen Brocks, of the Australian National University (ANU), describes Spongiophyton as “an extraordinary fossil, with exceptional preservation.”
“It is practically mummified, with organic matter intact. The tough material in simple plants is cellulose, but lichens are very different — they are composed of chitin, the same material that makes insects hard,” explains the researcher.
This feature was confirmed through chemical analyses that revealed a nitrogen signal never before observed. “It was a moment of scientific euphoria — a true ‘Eureka’ moment,” adds Brocks.
Lichens continue today to play a crucial role in soil formation, nutrient recycling, and carbon capture, especially in extreme environments, from deserts to polar regions. However, their origins remained an enigma due to the fragility of these organisms and the rarity of their fossils.
Co-author Nathaly L. Archilha, from the Brazilian Synchrotron Light Laboratory, highlights the importance of combining traditional techniques with advanced technologies:
“Initial measurements guided us to the most promising regions, allowing afterwards to collect 3D nanometric-scale images that revealed the complex networks of fungi and algae characteristic of lichens,” she explains.
The study involved more than 20 institutions and research centers in Brazil, Australia, the United States, the United Kingdom and France, in a collaboration that sheds new light on the role of lichens in the planet’s evolutionary history — the first to literally prepare the ground for all terrestrial life that followed.
