The Permian Extinction, alias “The Great Dying”, was sparked off by an enormous volcanic eruption that continued for almost one million years in what is today Siberia.
So far, the scientists were uncertain of how the so-called Flood Basalts eruption was responsible for the extinction of such a large percentage of life on Earth, as the previous volcanic activity of this magnitude hadn’t wiped out anywhere near as many species.
Some had hinted that the emission enveloped the Earth in a thick smog that barred the sunrays from reaching the planet’ surface.
However, the new findings reveal how the chemicals released by the emission emitted a large reservoir of toxic chemicals into the air that stripped off Earth’s ozone layer.
This incident led to the eradication of the only protection of Earth against the sun’s lethal UV rays, skyrocketing the death toll as compared to other massive eruptions.
Researchers at the Centre for Petrographic and Geochemical Research in Vandœuvre-lès-Nancy, France, examined rock from Earth’s upper mantle to ascertain the cause.
They studied the rock sections of the lithosphere – a section of the planet located between the crust and the mantle – that gets captured by passing magma and erupted to the surface during eruptions and the chemical make-up of mantle xenoliths.
By analyzing the ancient samples, scientists made an attempt to determine the constitution of the lithosphere.
They came to the conclusion that before the Flood Basalts occurred, the Siberian lithosphere was loaded with iodine, chlorine, and bromine heavily.
These chemicals that included elements from the halogen group seemingly disappeared quickly after the ruinous volcanic eruption.
The lead author of the study, Michael Broadley said, “’We concluded that the large reservoir of halogens that was stored in the Siberian lithosphere was sent into the earth’s atmosphere during the volcanic explosion. This effectively destroyed the ozone layer at the time and contributed to the mass extinction.”
252 million years ago, “The Great Dying” claimed lives of around 70% of life on land and around 95% of marine life.
Life in the Permian era appeared very different.
Reptiles — precursors to the crocodiles and dinosaurs that dominated the planet millions of years later, were the dominant land animals of the late Permian era.
Populating the land mass that is called now as Europe and North America were large herbivores, known as captorhinomorphs measuring between two and three meters in length (7 to 10 feet).
In the interim, the fossil plant record for the Permian era predominantly consists of mosses, seed ferns, and ferns, which were adapted to survive in the swampy environments and marshes that covered a large proportion of the planet.
Researchers believed that early protoangiosperms (precursors to flowering plants) showing a move towards drier areas started to emerge by the late Permian period.
However, the Permian seas were dominated by bony fishes with thick, heavy scales, and fan-shaped fins. The large reef communities that were home to squid-like nautiloids.
Ammonoids, that floated in the water with tightly coiled spiral shells were also widespread in the Permian fossil record.
The existing life on Earth has descended from the roughly 10% of microbes, plants, and animals that survived the mass extinction event.
Mr. Broadley further articulated, “The scale of this extinction was incredible. Scientists have often wondered what made the Siberian Flood Basalts so much more deadly than other similar eruptions.”