image: A paleo-art reconstruction of a scene from the late Early Triassic, showing a coastal mudplain to alluvial ecosystem in the Heshanggou Formation, North China
Credit: Mr J Sun (CC BY 4.0)
Tropical riparian ecosystems – those found along rivers and wetlands – recovered much faster than expected following the end-Permian mass extinction around 252 million years ago, according to new research.
The study, published February 14 as a Reviewed Preprint in eLife, is described by the editors as an important paper on the recovery of animal and plant life on land following the end-Permian mass extinction. They say the authors provide convincing evidence for a rapid recovery in tropical riparian ecosystems after a short phase of hostile environments, based on data from sediments, animal and plant fossils, and trace fossils from North China.
The end-Permian mass extinction occurred around 252 million years ago, and wiped out over 80% of marine species and 70% of terrestrial species due to extreme environmental changes including global warming, ocean acidification and prolonged droughts.
“Recovery in marine life after the end-Permian extinction has been extensively studied, but the timeline of ecosystem recovery in life on land is much less understood,” says lead author Dr Li Tian, Associate Researcher at the State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China. “Whereas it has long been theorised that low latitudinal land regions remained uninhabitable for an extended period of time, 7–10 million years after the extinction, our results suggest that some ecosystems were more adaptable than previously thought.”
To reconstruct the timeline of ecosystem recovery on land, Tian and colleagues analysed trace fossils (such as burrows and footprints), plant remains and vertebrate fossils preserved in sedimentary rocks spanning the Early Triassic, which followed the end-Permian extinction around 252–247 million years ago. These fossils were obtained from lake and river deposits in the central North China Basin. The team used a combination of techniques such as biostratigraphy, ichnology (the study of trace fossils), sedimentology and geochemical analyses.
Their studies suggest a harsh environment at the start of the Early Triassic period, with only sparse and simple life remaining. The fossils from this period indicate a monospecific community, meaning that only a single type of organism dominated, with little evidence of biodiversity. The fossils showed a notable reduction in organism size compared to before the end-Permian extinction – a common indicator of extreme environmental stress.
However, fossils from the Spathian stage (around 249 million years ago) showed an increase in plant stems, root traces, and signs of burrowing activity, suggesting a more stable and structured environment. The team also discovered fossils of medium-sized carnivorous vertebrates, indicating that multi-level food webs had been established by this stage. The resurgence of burrowing behaviour, which had largely disappeared after the extinction event, was a key finding. Burrowing behaviour plays an important role in aerating sediment and cycling nutrients in riparian ecosystems and suggests that animals during this time adapted to environmental stresses by escaping underground.
The findings challenge the view that ecosystem recovery on land after the extinction lagged significantly behind marine life, revealing that some ecosystems were already stabilising within a relatively short geological time frame.
The researchers note that further studies are needed to determine whether similar recoveries occurred in other land regions during the Early Triassic. Further evidence would help us to understand more about how life recovered from past mass extinctions and could offer valuable lessons about ecosystem resilience and adaptation in the face of modern climate change.
“Our study is the first to suggest that, contrary to past assumptions, life in tropical-subtropical riparian ecosystems rebounded relatively quickly after the end-Permian mass extinction,” concludes senior author Jinnan Tong, Principal Investigator at the State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences. “The fossil records we studied suggest that riparian zones played a crucial role in stabilising ecosystems after the extinction. Rivers and wetlands may have acted as refuges, providing more stable conditions that allowed life to rebound more quickly than drier, inland regions.”
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Journal
eLife
Article Title
Rapid riparian ecosystem recovery in low-latitudinal North China following the end-Permian mass extinction
Article Publication Date
14-Feb-2025