Prototaxites fossils are structurally and chemically distinct from extinct and extant Fungi

Corentin C Loron; Laura M Cooper; Sean Mcmahon; Seán F Jordan; Andrei V Gromov; Matthew Humpage; Niall Rodgers; Laetitia  Pichevin; Hendrik Vondracek; Ruaridh Alexander; Edwin Rodriguez Dzul; Alexander T Brasier; Michael  Krings; Alexander J Hetherington

doi:10.1126/sciadv.aec6277

Prototaxites fossils are structurally and chemically distinct from extinct and extant Fungi

Corentin C Loron^* (Corresponding Author)
, Laura M Cooper
, Sean Mcmahon
, Seán F Jordan
, Andrei V Gromov
, Matthew Humpage
, Niall Rodgers
, Laetitia Pichevin
, Hendrik Vondracek
, Ruaridh Alexander
, Edwin Rodriguez Dzul
, Alexander T Brasier
, Michael Krings
, Alexander J Hetherington^* (Corresponding Author)

^*Corresponding author for this work

Geology and Geophysics

Research output: Contribution to journal › Article › peer-review

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Abstract

Prototaxites was the first giant organism to live on the terrestrial surface, represented by columnar fossils of up to eight meters from the Early Devonian. However, its systematic affinity has been debated for over 165 years. There are now two remaining viable hypotheses: Prototaxites was either a fungus, or a member of an entirely extinct lineage. Here, we investigate the affinity of Prototaxites by contrasting its organization and molecular composition with that of Fungi. We report that fossils of Prototaxites taiti from the 407-million-year-old Rhynie chert were chemically distinct from contemporaneous Fungi and structurally distinct from all known Fungi. This finding casts doubt upon the fungal affinity of Prototaxites, instead suggesting that this enigmatic organism is best assigned to an entirely extinct eukaryotic lineage.

Original language	English
Article number	eaec6277
Number of pages	12
Journal	Science Advances
Volume	12
Issue number	4
Early online date	21 Jan 2026
DOIs	https://doi.org/10.1126/sciadv.aec6277
Publication status	Published - 23 Jan 2026

Bibliographical note

We thank I. Febbrari, Thin Sections and Lapidary Facility Manager, University of Edinburgh for the thin section preparation of Prototaxites; B. O’Connell (Cambridge University) for sedimentological advice; P. Orr (University College Dublin) for thin section preparation of Rhynie chert; N. Fraser, A. Ross, and Y. Candela for assistance accessioning material into National Museums Scotland; F. Buckley and North Sea Core for the assistance with Rhynie chert specimens; and P. Kenrick and N. Clark for access to historic P. taiti collections. We thank Gianfelice Cinque and Diamond Light Source for access to the MIRIAM beamline, B22 (proposal number SM33471-1) that contributed to the results presented here. This work was supported by funding for the Wellcome Discovery Research Platform for Hidden Cell Biology (226791) and we gratefully acknowledge support from the Light Microscopy Core.

Data Availability Statement

All data are available in the main text or the Supplementary Materials. Codes used to produce this work were deposited in the Zenodo repository DOI: 10.5281/zenodo.17632257 after archiving them from the GitHub https://github.com/nrodgers1/Prototaxites-Analysis-Code.

Funding

This work was supported by The Leverhulme Trust grant ECF-2023-202 (C.C.L.), Royal Society grant NIF\R1\211589 (C.C.L. and S.M.) and grant RGS\R2\212063 (A.J.H.), UK Research and Innovation Future Leaders Fellowship grant MR/T018585/1 and MR/Y03399X/1 (A.J.H.), Philip Leverhulme Prize grant PLP-2023-324 (A.J.H.), Human Frontier Science Program grant RGP006/2024 (S.M. and N.R.), European Research Council (E.R.C.) under the European Union’s Horizon Europe research and innovation program grant agreement no. 1101114969 (S.F.J.), Science Foundation Ireland grant 22/PATH-S/10692 (S.F.J.), Engineering and Physical Sciences Research Council grant EP/Y037138/1 (A.J.H.), and NERC E4 Doctoral Training Partnership (L.M.C. and R.A.).

Funders	Funder number
The Leverhulme Trust	ECF-2023-202, PLP-2023-324
The Royal Society	NIF\R1\211589, RGS\R2\212063
UK Research and Innovation	MR/T018585/1, MR/Y03399X/1
Human Frontier Science Program	RGP006/2024
European Research Council	1101114969
Science Foundation Ireland	22/PATH-S/10692
Engineering and Physical Sciences Research Council	EP/Y037138/1
Natural Environment Research Council

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Loron, C. C., Cooper, L. M., Mcmahon, S., Jordan, S. F., Gromov, A. V., Humpage, M., Rodgers, N., Pichevin, L., Vondracek, H., Alexander, R., Dzul, E. R., Brasier, A. T., Krings, M., & Hetherington, A. J. (2026). Prototaxites fossils are structurally and chemically distinct from extinct and extant Fungi. Science Advances, 12(4), Article eaec6277. https://doi.org/10.1126/sciadv.aec6277

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abstract = "Prototaxites was the first giant organism to live on the terrestrial surface, represented by columnar fossils of up to eight meters from the Early Devonian. However, its systematic affinity has been debated for over 165 years. There are now two remaining viable hypotheses: Prototaxites was either a fungus, or a member of an entirely extinct lineage. Here, we investigate the affinity of Prototaxites by contrasting its organization and molecular composition with that of Fungi. We report that fossils of Prototaxites taiti from the 407-million-year-old Rhynie chert were chemically distinct from contemporaneous Fungi and structurally distinct from all known Fungi. This finding casts doubt upon the fungal affinity of Prototaxites, instead suggesting that this enigmatic organism is best assigned to an entirely extinct eukaryotic lineage.",

author = "Loron, \{Corentin C\} and Cooper, \{Laura M\} and Sean Mcmahon and Jordan, \{Se{\'a}n F\} and Gromov, \{Andrei V\} and Matthew Humpage and Niall Rodgers and Laetitia Pichevin and Hendrik Vondracek and Ruaridh Alexander and Dzul, \{Edwin Rodriguez\} and Brasier, \{Alexander T\} and Michael Krings and Hetherington, \{Alexander J\}",

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AU - Cooper, Laura M

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AU - Gromov, Andrei V

AU - Humpage, Matthew

AU - Rodgers, Niall

AU - Pichevin, Laetitia

AU - Vondracek, Hendrik

AU - Alexander, Ruaridh

AU - Dzul, Edwin Rodriguez

AU - Brasier, Alexander T

AU - Krings, Michael

AU - Hetherington, Alexander J

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Prototaxites fossils are structurally and chemically distinct from extinct and extant Fungi

Abstract

Bibliographical note

Data Availability Statement

Funding

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