Ancient lichens paved the way for Earth’s first forests, but here's where it gets controversial: they might have done it all by themselves. A new study challenges the idea that trees were the pioneers of life on land, suggesting that lichens were the key players. These tiny organisms, a partnership between fungus and alga, were already widespread about 410 million years ago, long before complex forests took hold. The research, led by paleobiologist Bruno Becker-Kerber at Harvard University, reveals that lichens were not just marginal organisms but crucial pioneers in transforming Earth’s surface. The fossil record of Spongiophyton, a Devonian organism, is now recognized as a true lichen, with chemical and structural evidence supporting this claim. This discovery is significant because it highlights the role of lichens in creating the first thin layers of soil and stabilizing bare rock, essentially preparing the land for the arrival of trees. But here's the part most people miss: lichens were not just passive observers in this story. They were active participants, engineering landscapes and influencing the carbon cycle in ways that rippled outward. The power of early lichens is often underestimated. They helped rock crumble and made the first thin layers of soil. They trapped dust, unlocked nutrients, and built a base that roots could later use. Global analysis estimates that cryptogamic covers, which include lichens, mosses, and algae, fix roughly seven percent of terrestrial plant production. That might seem small, but it can tip local environments toward stability and growth. The study, published in the journal Science Advances, emphasizes the importance of lichens in the early stages of terrestrialization, the shift of life from water to land. It shows that stress-tolerant communities were already engineering landscapes before tall plants arrived. The fossil Spongiophyton, preserved like a mummified film, provides crucial evidence. The researchers used synchrotron scans to peer inside the fossil without destroying it, revealing calcite crystals forming layers near the outer surface and along filament walls. This biomineralization process is widespread in living lichens and often starts as calcium oxalate that later alters to calcite. Chemical tests further confirmed the lichen identity, showing abundant nitrogen compounds and alkyl-pyridines, which are signatures of chitin-rich fungal tissue. The spread of Spongiophyton across multiple Devonian rock layers and sites suggests that lichens were ecologically prominent just before complex forests expanded. This fossil likely thrived in the cold, high-latitude parts of Gondwana, today’s South America and Africa, which fits the hardy nature of lichen communities in harsh settings. The anatomy of Spongiophyton does not cleanly match major modern fungal groups, hinting at early branches of lichenized fungi that left no direct descendants. However, evidence from internal pores and surface layers suggests gas exchange features that echo structures in some living groups, strengthening the case that this was a lichen, not an alga or simple plant. The study's findings have significant implications for our understanding of Earth's history and the role of lichens in shaping the planet. Lichens today still perform many of the same tasks their Devonian ancestors did. They colonize bare rock, release acids that help form soil, and anchor microscopic ecosystems in places where few other organisms can survive. On mountainsides, deserts, and polar plains, lichens are still quiet builders of habitability. Researchers studying Earth’s early climate point out that these simple partnerships continue to shape carbon cycles on a global scale. By capturing and storing carbon in their tissues and the soil beneath them, lichens act as subtle climate regulators, linking the story of life’s beginnings to the planet’s ongoing balance. The lessons from Earth’s first builders are profound. Early land was patchy and raw, with rock, dust, and shallow soils. Lichen mats would have stabilized surfaces, slowed erosion, and supplied organic matter to build thicker soils. They also would have affected carbon and nutrient cycling in ways that rippled outward. Even today, cryptogamic covers, thin communities that live without seeds or flowers, are major players in carbon and nitrogen budgets. Future work can test other enigmatic fossils with the same toolkit. If more pre-forest lichens turn up, models of Devonian climate and weathering will need an update. For now, this fossil partnership gives credit where it is due. Before roots ran deep, lichens were already doing the quiet work that made land livable. The study is published in the journal Science Advances.
