Mystery Prototaxites tower fossils may represent a newly discovered kind of life
January 21, 2026
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Mysterious Tower Fossils May Come From Newly Discovered Type of Life
Imposing Prototaxites ruled the Earth before trees – and they may have been an entirely new form of life for science
Reconstruction of Prototaxites taiti, which could reach the height of a telephone pole, growing in the 407 million year old Rhynie chert ecosystem.
Matt Humpage, Northern Rogue Studios
Before trees appeared about 400 million years ago, our planet’s landscape was dominated by enigmatic, arrow-shaped life forms that rose more than 25 feet from the ground. Their trunk-shaped fossils were discovered in 1843. Yet despite more than a century of speculation, scientists have struggled to answer the most fundamental question about Earth’s original land giants: What were they?
According to a new study, this could be because they belonged to a previously unknown branch of life.
The first person to examine this biological misfit did so in 1855, and in 1859 he dubbed it Prototaxiteswhich means “early yew”. The name stuck, although experts soon realized that this organism was not a tree at all. Perhaps it was some kind of terrestrial kelp or a megalithic mushroom? “It feels like it doesn’t fit comfortably anywhere,” says Matthew Nelsen, a senior research scientist at the Field Museum of Natural History, who was not involved in the new study. “People have tried to fit it into these different groups, but there are always things that don’t make sense.”
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Over time, two main hypotheses have emerged: either Prototaxites was an ancient mushroom, or it belonged to a category of its own. Now, after comparing fossils of these cryptic organisms with fossil fungi from the same rock deposit, the authors of the new study, published today in Scientific advances, conclude that Prototaxites was probably a distinct lineage. This would place it on an equal footing with the six currently recognized kingdoms of life: those of plants, animals, fungi, protists, bacteria and archaea.
A fossil specimen of Prototaxites taiti shows its uneven internal structure.
Laura Cooper, University of Edinburgh
Prototaxites was composed of intertwined tubes, giving it a superficial resemblance to mushrooms. But the anatomical similarities end there. The researchers discovered that PrototaxitesThe tubes branch enormously, while the threadlike hyphae of modern fungi follow more orderly patterns. Additionally, the researchers detected no chemical traces of chitin, a polymer found in the cell walls of all living fungi and in fossil fungi preserved alongside Prototaxites. “It doesn’t seem to have the characteristics of living fungal groups,” says Laura Cooper, co-senior author of the study. student at the University of Edinburgh.
It wasn’t completely unexpected. In a 2022 paper co-authored by Nelsen with paleobotanist Kevin Boyce of Stanford University, the researchers argued that “if Prototaxites was indeed of fungal origin, it may represent part of an extinct lineage” – in other words, it was already distinct from other fungi. Boyce is agnostic as to where Prototaxites truly belongs, and he’s not yet ready to kick him out of the fungal kingdom. But he notes that even though the organism is just a strange fungus, it has independently evolved a unique form of complex multicellular life. “Whatever’s happening,” Boyce says, “it’s a weird thing that’s doing its own thing.”
Prototaxites taiti dominates the surrounding landscape in a paleoenvironmental reconstruction of the 407-million-year-old Rhynie hot springs chert ecosystem.
Matt Humpage, Northern Rogue Studios
Cooper supports Prototaxites “was so fundamentally different from the mushrooms we see today” that “trying to introduce it into mushrooms is not productive.” Whether or not this study settles the question of taxonomy, there is still much to learn. Previous work by Boyce shows that Prototaxites probably played an ecological role similar to that of mushrooms: consuming rotting organic matter. But little organic matter was available. In a world of ankle-high plants, these organisms grew like telephone poles. “How this actually works energetically,” Cooper says, “is still a complete mystery.”
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