Fossils in China suggest the Great Dying was not so devastating in some areas. (Photo: YANG Dinghua)
The mass extinction that wiped out 80% of all life on Earth 250 million years ago may not have been so catastrophic for plant life, new fossils suggest. Scientists have found refuge in China, where plants appear to have survived the horrific event.
The end-Permian mass extinction, known as the Great Dying, occurred 251.9 million years ago. At the time, the supercontinent Pangaea was breaking up, but all of Earth’s landmasses were still largely united, with the newly formed continents separated by shallow seas. Massive eruptions from a volcanic system known as the Siberian Traps appear to have led to extremely high levels of carbon dioxide: a 2021 study found that atmospheric CO2 reached 2,500 parts per million (ppm) during this period, compared to 425 ppm today. This caused global warming and ocean acidification, which in turn led to the massive collapse of marine ecosystems.
The situation on land remains much more uncertain. Only a few places on the planet contain rock layers containing fossils from late Permian and early Triassic land ecosystems.
A new study of one such site in what is now northeast China has found a refuge where the ecosystem remained relatively healthy despite the Great Dying, with gymnosperm seed forests continuing to grow, complete with spore-bearing ferns.
“At least in this location, we're not seeing mass vegetation die-off,” study co-author Wan Yang, a professor of geology and geophysics at the Missouri University of Science and Technology, told Live Science.
The findings, published Wednesday (March 12) in the journal Science Advances, support the idea that the Great Dying process was more complex on land than in marine ecosystems, Young said.
A fossilized conifer tree trunk from the end-Permian mass extinction, found in modern-day northeastern China. The Great Change?
Yang and his team examined rock layers in Xinjiang that spanned the period of the mass extinction.
The main advantage of this now-desert region is that the rocks contain layers of ash that contain tiny crystals called zircons. Zircons contain radioactive elements such as lead and uranium that gradually decay, helping researchers determine the age of the
Sourse: www.livescience.com
