Palaeontology: How ancient plants survived a mass extinction (Nature Ecology & Evolution )
21 April 2026
Insights into how ancient plants lived around 252 million years ago at the time of the Permian–Triassic mass extinction, the most severe loss of biodiversity in Earth’s history, are reported in Nature Ecology & Evolution. The findings could provide insights into how some modern plants may respond to severe future climate-warming scenarios.
The Permian–Triassic mass extinction, also known as the ‘Great Dying’, was driven by massive volcanic eruptions that led to globally catastrophic warming, elevated atmospheric carbon dioxide levels, widespread ocean anoxia (low oxygen levels in seawater) and ocean acidification. Major changes in land vegetation followed. Forests that once covered large regions were replaced by simple, low-diversity plant communities dominated by lycophytes (small primitive vascular plants). Understanding how these plants persisted may help to explain how land ecosystems recovered after this crisis.
Zhen Xu and colleagues studied 285 lycophyte fossils from Southwest China and 200 from previously recorded literature and compared their features with those of living and fossil relatives. The Permian–Triassic lycophytes show affinities with today’s quillworts (very small, often semiaquatic plants). Their carbon isotope signatures are relatively enriched compared with co-occurring plants, a pattern similar to that observed in modern quillworts and consistent with stress-induced shifts in photosynthesis towards a more flexible and water-efficient pathway known as crassulacean acid metabolism (CAM). This adaptation may have helped these plants to survive the extreme environmental conditions of the Early Triassic (251–246 million years ago). Climate simulations indicate that these lycophytes lived in regions where maximum daily temperatures regularly exceeded 40 °C and may have reached as high as 65 °C in some local surface conditions.
These findings suggest that the ability to use CAM may have helped these lycophytes to endure extreme heat and high carbon dioxide levels. Today, CAM photosynthesis is found particularly in a wide range of flowering plant groups, where it has evolved multiple times independently, highlighting its importance as a flexible adaptation to extreme environments. However, the authors note that the fossil record from this time is sparse and not all plant groups can be directly compared, so some uncertainty remains.
- Article
- Open access
- Published: 20 April 2026
Xu, Z., Hilton, J., Yu, J. et al. CAM photosynthesis may have conferred an advantage during the Permian–Triassic mass extinction event. Nat Ecol Evol (2026). https://doi.org/10.1038/s41559-026-03026-0
News & Views: Flexible photosynthesis at the end Permian
https://www.nature.com/articles/s41559-026-03052-y
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