Prototaxites
| Prototaxites Temporal range:
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|---|---|
| Branching apex of P. loganii, "Schunnemunk tree" | |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | incertae sedis |
| Family: | †Prototaxitaceae Hueber |
| Genus: | †Prototaxites Dawson, 1859 |
| Type species | |
| Prototaxites loganii Dawson, 1859
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| Species | |
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| Synonyms | |
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Prototaxites is an extinct genus of large macroscopic eukaryote dating from the Late Silurian until the Late Devonian periods. Prototaxites formed large trunk-like structures up to 1 metre (3 ft) wide, reaching 8 metres (26 ft) in height, made up of tiny interwoven tubules around 50 micrometres (0.0020 in) in diameter, making it by far the largest land-dwelling organism of its time.
The taxonomy of Prototaxites has long been the subject of debate. It is widely considered a fungus, but the debate is ongoing. Its exact relationship with extant fungus lineages is uncertain. It was almost certainly a perennial organism that grew over multiple years. Several ecologies have been proposed, including that it was saprotrophic like many modern fungi, or that it was a lichenised autotroph. Recent research challenges this claim and proposes that Prototaxites is not a fungus, but belongs to a new kingdom of eukaryotic life.