The catastrophe called the Great Dying, which occurred between the Permian and Triassic periods wiped out 90 percent of the planet's marine life and 70 percent of all plant and animal life. The most recent popular scientffic belief about what caused it was the impact of a large object from space, but the examination of sediment and fossils deposited at the time has led two groups of scientists to revise this belief.
Animals and plants both on land and in the sea were dying at the same time and apparently from the same causes - 'too much beat and too little oxygen,' said Peter Ward, a University of Washington paleontologist. In their research published in Science Express, the groups found increased levels of sulphur and depleted oxygen in the ancient rock. Ward and his team of researchers from the United States and South Africa thought that the sulphur came from continued volcanic eruptions in an area known as the Siberian Trap. The eruptions warmed the Earth, trapped sunlight, and depleted oxygen in the air.
At the same time, the Earth's shifting tectonic plates lowered the levels of the ocean, exposing seabeds and releasing methane trapped in the sediment there, further increasing the global warning. The temperatures kept rising so that it got hotter and until it reached a critical point causing everything to die. Temperatures around the world rose 8 degrees, killing off plants which served as food animals, therebystarving them. In addition, oxygen levels dropped to about 16 percent the atmosphere, whereas normal levels today are at 21.
Therefore, it is believed that widespread volcanic eruptions that led to global warning was likely the cause of massive extinction 250 million years ago, not the impact of an asteroid of comet
Which of the following is NOT the cause of the massive extinction millions of year ago?