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In the face of mass extinction events, survival spots are rare. However, research suggests that the Turpan-Hami Basin in China’s Xinjiang Autonomous Region may have acted as a sanctuary for some species. This area potentially served as a refugium during the end-Permian mass extinction, a catastrophic period that resulted in the loss of 80 to 90 percent of Earth’s species around 252 million years ago.
Recent findings published on March 12 in the journal Science Advances provide new insights into the impact of this mass extinction on terrestrial ecosystems, challenging prior assumptions that land-based environments were similarly devastated as marine habitats during this turbulent epoch of Earth’s history.
Debating the Great Dying
The end-Permian mass extinction, often termed the Great Dying, saw approximately 80 percent of marine species vanish. Although land species also suffered significant declines, the extent of their loss has been a topic of scientific debate.
One dominant theory postulates that extensive volcanic eruptions in present-day Siberia unleashed environmental chaos, resulting in wildfires, acid rain, and the release of toxic gases. This perspective is supported by the extinction of plants like Gigantopteris in regions spanning South China and other parts of ancient Gondwanaland during the event.
[ Related: Mega El Niños contributed to massive species loss. ]
Conversely, another hypothesis suggests that certain geographic and atmospheric conditions, including latitude and atmospheric circulation, mitigated the effects of these catastrophic events in specific areas. Some fossil records indicate the presence of Mesozoic plants that survived prior to the extinction, suggesting an ongoing evolutionary process.
Fossil Evidence: Tree Trunks and Fern Stems
The recent study conducted by a multidisciplinary team from the United States, Tibet, and China analyzed fossil evidence from a plant community in the South Taodonggou section of the Turpan-Hami Basin. The findings indicate that a significant portion of the vegetation persisted throughout the extinction phase, facilitating quicker recovery and continuity of evolution.
The researchers utilized advanced geological dating techniques and detailed analyses of fossil pollen and spores. They discovered that the fern fields and conifer forests in this location survived not just until the onset of the extinction but also thrived for 160,000 years following its conclusion.
Artistic reconstruction of the ecological landscape at the onset of the end-Permian mass extinction based on fossil evidence. CREDIT: Image by Dinghua Yang.
Mingli Wan, a co-author of the study, emphasized that the presence of well-preserved tree trunks and fern stems supports the notion that these microfossils represent local vegetation rather than remnants transported from elsewhere.
Although some local plant species faced extinction, the overall decline of spore and pollen species in South Taodonggou was limited to around 21 percent, contrasting sharply with the marine extinction rate of about 80 percent during that era.
Understanding ‘Biological Resilience’
The researchers assert that this stable vegetative foundation played a vital role in the local ecosystem’s recovery. Fossil records suggest the presence of diverse tetrapods, including the herbivorous Lystrosaurus and predatory chroniosuchians, indicating a rapidly complexifying food web. This evidence points to a recovery rate that was more than ten times faster compared to other global regions.
The region’s consistent semi-humid climate played a key role in fostering this biological resilience. The South Taodonggou area received about 100 millimeters of rainfall annually, allowing for the development of lush vegetation, which in turn supported a more populous local ecosystem post-extinction.
Tetrapod skeletal fossils from the South Taodonggou section date to approximately 150,000 years before the end-Permian mass extinction. CREDIT: Nanjing Institute of Geology and Palaeontology (NIGPAS) of the Chinese Academy of Sciences.
Notably, the Turpan-Hami Basin’s closeness to the volcanic activity that precipitated the mass extinction may have paradoxically provided a refuge for diverse forms of life.
Feng Liu, another co-author, observed that this research illustrates how local climatic and geographical attributes can create unexpected shelters of resilience. Such findings are particularly relevant today as humanity grapples with the potential for a new mass extinction driven by human actions. The study underscores the need to identify and preserve regions like the Turpan-Hami Basin that could safeguard life in changing environmental conditions.
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