Fungi existed millions of years before the first trees

Introduction: a biological kingdom far older than we think

A misconception worth correcting

When we picture the first land ecosystems, we tend to imagine primeval forests full of majestic trees, with fungi quietly growing at their base, almost like a secondary backdrop. The actual chronology is reversed. Fungi already existed, and were thriving, tens of millions of years before the first tree ever appeared on Earth. A precedence that overturns the classic picture we have of the history of terrestrial life and the order in which the great kingdoms of the living world emerged.

The oldest fossils attesting to the presence of fungi date back more than 400 million years, while the first trees don't show up in the fossil record until roughly 380 million years ago. A gap of several tens of millions of years, meaning fungi shaped early terrestrial ecosystems well before the arrival of forests as we know them today, with their trunks, canopies, and deep roots.

The Rhynie deposit, an exceptional window into the past

This precedence has been documented through rigorous paleobotanical studies, confirmed in particular by the analysis of exceptional fossils from the Rhynie chert deposit in Scotland. This site, famous among paleontologists worldwide, preserved organisms dating back roughly 400 million years in a silica rock called chert, with a rare level of detail that lets scientists observe microscopic fungal structures that stayed intact for hundreds of millions of years.

Scientists studying this deposit consider it one of the most precious geological archives for understanding the beginnings of life on dry land. Every new analysis of these rocks provides additional detail on the diversity and complexity of the fungal organisms that already populated our planet well before the first tree trunk ever appeared.

Why this timeline was long misunderstood

A bias tied to fossil visibility

For a long time, the role of fungi in the history of terrestrial life was underestimated, partly because their structures are far more fragile and harder to fossilize than wood or the woody structures of plants. Trees, with their solid trunks, leave obvious, massive fossil traces, while the microscopic filaments of fungi, called hyphae, require exceptional preservation conditions to survive geological ages without fully decomposing.

This difference in preservation long gave the misleading impression that fungi were relatively recent or secondary organisms in the history of life, when in fact they occupied a fundamental, early place in terrestrial ecosystems, well before woody plants came to dominate the landscape and radically transform the planet's surface.

Increasingly precise analytical methods

Advances in microscopy and chemical rock analysis have allowed researchers to detect fungal traces far older and more subtle than earlier methods could ever reveal. These technical advances have gradually exposed the true extent of fungal presence in early land ecosystems, helping to revise the timeline long accepted in paleobotany textbooks.

New high-resolution imaging techniques now let scientists distinguish cellular details that were completely out of reach just a few decades ago. This added precision has confirmed, fossil after fossil, that fungi occupied a far older and more central position in evolutionary history than previously believed.

The fundamental role of early fungi

Pioneers of organic decomposition

Before trees appeared, fungi already played a fundamental ecological role: the decomposition of organic matter. By breaking down the tissues of the earliest, still modest and non-woody land plants, fungi actively contributed to recycling nutrients in an environment where this process was still being established. This decomposer function has remained, to this day, one of the most essential ecological roles played by the fungal kingdom across the entire planet.

This decomposition work directly contributed to the formation of the planet's first fertile soils, an indispensable step that later allowed increasingly complex plants to develop, all the way up to trees themselves. Without this prior fungal activity, the evolution of terrestrial ecosystems as we know them would likely have followed a radically different, slower, and more chaotic path.

Early symbiotic partnerships with plants

Early fungi did not just decompose organic matter: some also formed symbiotic relationships with the first land plants, a mechanism known today as mycorrhiza. These associations, in which the fungus helps the plant absorb water and nutrients from the soil in exchange for sugars produced through photosynthesis, have existed for hundreds of millions of years and likely played a decisive role in plants' ability to permanently colonize dry land.

This ancient collaboration between fungi and plants shows just how closely the two kingdoms developed together from the very first moments of terrestrial life, long before trees became the plant giants we know today. This biological alliance remains, even now, one of the most widespread and essential in the plant world.

What fossils teach us about these ancient organisms

Forms that were already surprisingly diverse

Fossils found at Rhynie and elsewhere reveal that early fungi already displayed a surprising diversity of forms for such a distant period in the history of life. Some resembled simple filamentous structures, others showed more complex organization, suggesting that diversification within the fungal kingdom had already begun well before the great forests and their many plant layers appeared.

This early diversity contradicts the idea of a linear, progressive evolution in which simple organisms would always strictly precede complex forms chronologically. Fungi appear to have explored several different evolutionary strategies very early on, well before land plants underwent their own explosion in diversity and structural complexity.

A timescale that's hard to grasp

Picturing a gap of several tens of millions of years remains a difficult exercise for the human mind, accustomed to reasoning on far shorter timescales. To put it in perspective, modern humans have existed for roughly 300,000 years — a mere instant compared with the 400 million years separating the earliest known fungi from our own appearance on Earth.

This disproportion in scale shows just how limited our intuitive perception of geological time really is. Paleontologists constantly have to juggle these enormous orders of magnitude, where a few million years can amount to little more than a blink at the scale of the entire history of life on Earth.

Why this precedence changes our view of evolution

Rethinking classic scenarios of land colonization

This revised timeline calls for rethinking the classic scenarios of colonization of dry land by living organisms. Far from being simple, quiet companions to trees, fungi emerge as pioneering players, almost invisible architects, who prepared the ecological and chemical groundwork necessary for the later establishment of complex, lasting forest ecosystems.

This view reinforces the idea that the evolution of terrestrial life did not unfold as a simple progression of increasingly complex organisms, but rather as a tangle of ecological relationships in which different kingdoms of the living world mutually shaped one another over tens of millions of years of shared history.

Implications for current research

Understanding this fungal precedence today helps researchers better model the evolution of early biogeochemical cycles, notably those of carbon and nitrogen, essential to understanding the planet's ancient climate. This work also feeds into reflection on the current resilience of forest ecosystems, where underground fungal networks continue to connect and exchange resources between plants.

Researchers in modern ecology increasingly draw on this ancient data to understand how today's forests respond to environmental change. The parallel between primitive fungal networks and contemporary mycorrhizal networks offers a valuable perspective on the continuity of ecological mechanisms across hundreds of millions of years.

What this story teaches us about our relationship with the living world

The mysterious Prototaxites, a giant without a forest

Even before trees appeared, certain fungal organisms reached impressive sizes, exemplified by the famous Prototaxites, a fossil structure that could exceed eight meters in height and whose exact nature long divided the scientific community. For decades, researchers debated whether it was a giant fungus, an alga, or a lichen, since its morphology resembled nothing known in today's plant kingdom. This giant literally dominated the terrestrial landscape at a time when no plant stood taller than a few dozen centimeters.

Giving overdue credit to a neglected kingdom

The fungal kingdom remains, even today, significantly underrepresented in popular science culture compared with the animal and plant kingdoms. This chronological precedence of fungi over trees should nonetheless encourage us to give them a more central place in the story we tell about the history of life on Earth, given how decisive their role was from the very origins of terrestrial ecosystems.

Mycologists, the specialists who study fungi, regularly point out that this biological kingdom constitutes a full branch of the tree of life, just as ancient and just as rich in diversity as those of plants or animals. Recognizing this precedence and this ecological importance contributes to a better overall understanding of our natural environment.

An invitation to look at nature differently

This discovery invites everyone to take a fresh look at the fungi we come across every day, whether in a forest, a garden, or even a simple box of button mushrooms. These organisms, seen today as discreet and secondary, actually descend from a lineage that literally prepared the ground for all terrestrial plant life.

Understanding this fungal precedence also helps clarify why underground networks of fungi still play such a decisive role today in forest health, soil fertility, and even certain climate cycles essential to our planet's balance.

Conclusion: fungi, the quiet architects of terrestrial life

A precedence now firmly established

The fossil evidence gathered over decades, particularly from the Rhynie deposit, firmly establishes that fungi preceded trees on dry land by several tens of millions of years. This precedence is no longer a marginal hypothesis, but a documented reality supported by converging paleobotanical studies conducted across several continents using varied and complementary analytical methods.

This discovery calls for revisiting the place we generally give fungi in the history of life: far from being simple secondary organisms, they were founding players in the earliest terrestrial ecosystems, with a decisive role in soil formation and the later development of complex plants, trees included.

A lesson in humility in the face of deep time

The next time you come across a mushroom on a walk through the woods, remember that its distant ancestors already occupied the surface of our planet long before the first tree ever put down roots. A precedence that calls for a renewed perspective on organisms too often seen as mere curiosities of the undergrowth, when they were in fact pioneers of terrestrial life.

By Maxime Marquette, columnist

Sources

Primary sources

Nature — Subject page Palaeontology, reference resources on ancient fossils — 2026

Smithsonian Institution — Spotlight on Ancient Fungi, resources on the evolutionary history of fungi — 2026

Proceedings of the National Academy of Sciences — Reference publications in paleobotany — 2026

Secondary sources

Futura-Sciences — Planet section, science coverage on the history of terrestrial life — 2026

Sciences et Avenir — Science news on paleobotany — 2026

National Geographic France — Science section, coverage on fungal evolution — 2026