Evrim Yazgin
Cosmos science journalist
Fossils found in China’s Turpan-Hami Basin reveal a refuge, or “life oasis”, for plants and animals during the Permian extinction – the worst mass extinction in Earth’s history.
The findings suggest the end-Permian extinction 252 million years ago did not affect terrestrial environments as much as marine ecosystems, challenging previous beliefs about the scale of the catastrophe.
Known as the “Great Dying,” the Permian extinction wiped out about 90% of marine species.
Fossil evidence suggests that about 57% of all biological families on Earth were wiped out. The Permian-Triassic extinction event spelled the end of the Palaeozoic era and paved the way for the emergence of the dinosaurs.
While palaeontologists estimate about 70% of terrestrial organisms died out during the period, the effect of the mass extinction on land has long been debated.
Geological evidence suggests that the extinction was caused by volcanic eruptions in Siberia which led to wildfires, acid rain, the release of toxic gases and global warming. Plants such as the Gigantopteris flora in South China and across the southern continents disappearing at the end of the Permian.
But some palaeontologists have argued that the devastation was not felt equally everywhere on land.
An assemblage of fossils discovered at South Taodonggou in China’s northern Xinjiang province points to an area of land shielded from the worst effects of the extinction. Pockets of resilience like this would have been crucial in the ability of life to rebound on Earth after the Great Dying.
The fossils are detailed in a paper published in the journal Science Advances.
Some of the fossils belong to plants which were previously thought to only have existed during the Mesozoic, or “Age of Dinosaurs”.
The South Taodonggou pollen and spore fossils show a thriving ecosystem of riverbank fern fields and coniferous forests which lasted from 160,000 before the Permian ended, and lasting another 160,000 after the mass extinction.
“The presence of intact tree trunks and fern stems further confirms that these microfossils represent local vegetation, not transported remnants,” says WAN Mingli from the Nanjing Institute of Geology and Palaeontology (NIGPAS) of the Chinese Academy of Sciences.
The discovery of many “missing” species in Early Triassic rocks suggests the overall extinction rate of spore and pollen species in the South Taodonggou section was as low as 21%.
And it wasn’t just plants that thrived in the area.
Stable vegetation was vital to the rapid recovery of the ecosystem. Fossils from 75,000 years after the end of the Permian include land vertebrates. Among them are the herbivorous stem mammal Lystrosaurus and carnivorous, crocodile-like chroniosuchians.
The complex food web and local diversity suggests the area recovered about 10 times faster than other regions around the world.
One possible explanation for the “life oasis” at South Taodonggou could be that the area consistent rainfall of about 1,000mm.
“This suggests that local climate and geographic factors can create surprising pockets of resilience, offering hope for conservation efforts in the face of global environmental change,” says LIU Feng from NIGPAS.
The researchers add that the identification and protection of natural refuges today is critical as Earth is going through its 6th mass extinction driven by human activity.
