The Late Permian Mass Extinction Explained


Mass extinctions are evolutionary turning points – brief moments on a geologic timescale that radically change the course of life on earth. One moment in particular stands out. The Permian-Triassic extinction, aka the Great Death, eradicated more than 90 percent of the earth’s marine species and 75 percent of terrestrial species 252 million years ago. It was the deadliest mass extinction event in our planet’s history, and its legacy lives on in the flora and fauna of the modern world.

The climatic and geochemical triggers of the Great Death are eerily similar to the effects of anthropogenic climate change. Global warming, ocean acidification and ozone depletion have caused ecological collapse.

Organisms that recovered from extinction did so slowly. The equatorial regions, which had been burned beyond recognition, have not regained their characteristic biodiversity for five million years. Global ecosystems lacked both diversity and stability for at least eight million years after the event.

The survivors of the extinction event, though few in number, eventually repopulated the earth. These organisms are the ancestors of all living things today. For paleontologists, the late Permian mass extinction is the temporal boundary between ancient Paleozoic fauna and modern fauna – a theoretical boundary between our world and a barely recognizable predecessor.

find the precision

From the end of the 2000s, the research community was considerably divided on what caused the Permian extinction. Some have suggested that volcanism was involved, while others have suggested a meteor impact, like the one that wiped out the dinosaurscaused the extinction.

Those who preferred the volcanic explanation, suspected the siberian traps, a vast region of volcanic rock in present-day Siberia. The formation developed during an unparalleled period of volcanic rock on the ancient supercontinent Pangea.

“This is the largest continental volcanic event and the largest mass extinction ever known on Earth,” says Dr. Lindy Elkins-Tanton, planetary scientist and professor at Arizona State University. “At the time, we didn’t know what was causing one or if they were definitely related to each other.”

In 2014, Chinese and American researchers makes a breakthrough. The team extracted ancient volcanic ash from the section and tip of the global stratotype for the early Triassic period, a site in Meishan, China, which contains sediments that date unambiguously to the Crisis. By analyzing the isotopes of uranium and lead contained in the ashes, they put a relatively precise date on the extinction: 251.9 million years ago, more or less 70,000 years.

The next step was to date the Siberian traps. Using the same method, scientists samples analyzed of the construction site. “Most of this diffusive, explosive volcanism led to extinction,” says Elkins-Tanton, who was part of the research team.

From these two dates, a chronology began to take shape. Intense volcanic activity on the ancient supercontinent of Pangea has spewed magma through layers of basalt, coal and organic matter. The burning of these layers produced an immense amount of CO2 as well as other greenhouse gases and chlorofluorocarbons.

Victims and survivors

On land, plants and animals perished in the equatorial regions. At more remote latitudes, mosses and other lycopods began to dominate the ecosystems which were once wooded with conifers. Our ancestors, the tetrapods, mass death. The survivors fled the tropics to the poles.

As the mass extinctions before him, the end of the Permian had an inordinate impact on marine organisms. When CO2 from the atmosphere seeps into the water, the ocean has become more and more acidic. Simultaneously, high temperatures and cyanobacterial blooms consumed dissolved oxygen until little was left.

Many organisms that had evolved to build exoskeletons from minerals, found in ambient seawater, did not survive these changes in marine chemistry. The engineers of the Permian reef ecosystems, the rugose and tabulate corals, have completely disappeared. Large groups of outer-shelled cephalopods, ancestors of the nautilus, succumbed to the same fate. The end of the Permian also extinguished the last species of trilobites, a group that had been in decline since the Ordovician mass extinction.

Read more: The first mass extinction event explained: the end of the Ordovician

As with any mass extinction, there were survivors of the Great Death. Before the event, clam-like brachiopods were many and variedbut extinction extinguished them for the benefit of their cousins, the bivalve molluscs. To date, bivalves are widespread, while only a few orders of brachiopods remain.

Many researchers have speculated that the end of the Permian may have catalyzed diversification among tetrapods. Although the extinction wiped out many people permanently, the Early Triassic saw the creatures diversify and rapidly expand their range. This “radiation” eventually gave rise to archosaurs and later dinosaurs.

Draw parallels

The same factors that drove anthropogenic global warming today led to global ecological collapse at the end of the Permian. An overabundance of greenhouse gases has made the planet uninhabitable for most living organisms. Really, the warming that initiated the end of the Permian may have occurred at a much slower rate than anthropogenic global warming.

“It was the same climate change caused by the same greenhouse gases that we see today,” says Elkins-Tanton. “And that was almost the end of multicellular life on earth.”

However, climatologists predict that if we manage to reduce our emissions fast enough, we can keep global warming to levels far below those that scorched the earth during the Earth’s greatest extinction event. It is not too late to avoid total and complete ecological collapse.

“The rate of change may not have been as rapid as it is today, but it has changed the temperature so much that it is really the worst-case scenario of what could happen,” David Botter said, paleoecologist and professor of earth sciences at the University of Southern California. “That’s why we should study it. To understand the future scenarios of our climate.

The future scenario, most analogous to the late Permian, would see humans continue to burn fossil fuels until there are few surviving organisms left. It’s a scenario that may not represent the end of life on earth, but a fundamental change from which it would take millions of years to bounce back.


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