Microscope image of zircon crystals separated for U-Pb isotopic dating from the latest Permian ash bed at Penglaitan. Credit: Jahan Ramezani
Sept. 19, 2018 (Phys.org) -- The most severe mass extinction in Earth's history occurred with almost no early warning signs, according to a new study by scientists at MIT, China, and elsewhere.
The end-Permian mass extinction, which took place 251.9 million years ago, killed off more than 96 percent of the planet's marine species and 70 percent of its terrestrial life -- a global annihilation that marked the end of the Permian Period.
The new study, published today in the GSA Bulletin, reports that in the approximately 30,000 years leading up to the end-Permian extinction, there is no geologic evidence of species starting to die out. The researchers also found no signs of any big swings in ocean temperature or dramatic fluxes of carbon dioxide in the atmosphere. When ocean and land species did die out, they did so en masse, over a period that was geologically instantaneous.
"We can say for sure that there were no initial pulses of extinction coming in," says study co-author Jahandar Ramezani, a research scientist in MIT's Department of Earth, Atmospheric, and Planetary Sciences. "A vibrant marine ecosystem was continuing until the very end of Permian, and then bang -- life disappears. And the big outcome of this paper is that we don't see early warning signals of the extinction. Everything happened geologically very fast."