Huey and UW paleontologist Peter Ward are authors of a paper detailing the work, published in the April 15 edition of the journal Science. The work was supported by grants from the National Science Foundation and the National Aeronautics and Space Administration's Astrobiology Institute.
Not only was atmospheric oxygen content dropping at the end of the Permian, the scientists said, but carbon dioxide levels were rising, leading to global climate warming.
"Declining oxygen and warming temperatures would have been doubly stressful for late Permian animals," Huey said. "As the climate warms, body temperatures and metabolic rates go up. That means oxygen demand is going up, so animals would face an increased oxygen demand and a reduced supply. It would be like forcing athletes to exercise more but giving them less food. They'd be in trouble."
Ward was lead author of a paper published in Science earlier this year presenting evidence that extinction rates of land vertebrates were elevated throughout the late Permian, likely because of climate change, and culminated in a mass extinction at the end of the Permian. The event, often called "the Great Dying," was the greatest mass extinction in Earth's history, killing 90 percent of all marine life and nearly three-quarters of land plants and animals.
Ward said paleontologists had previously assumed that Pangea was not just a supercontinent but also a "superhighway" on which species would have encountered few roadblocks while moving from one place to another.
However, it appears the greatly reduced oxygen actually created impassable barriers that affected the ability of animals