Reduced Oxygen Contributed to "Great Dying" (Image 2)
The red line shows atmospheric oxygen amounts over time. The black line indicates the altitude in today's atmosphere where that amount of oxygen is found. When oxygen levels were at their lowest, around 240 million years ago, an animal living at sea level would have experienced oxygen availability similar to that today at 17,400 feet.
As atmospheric oxygen decreased in the late Permian period, hypoxia, or insufficient oxygen in bodily tissue, would have become an undeniable problem for Earth's terrestrial species. National Science Foundation-supported researchers predicted that eventually, because oxygen levels decrease as altitude increases, only land near sea level would have been habitable on the relatively new supercontinent of Pangaea. As a result of this so-called "altitudinal compression," even modestly high mountains would have represented insurmountable barriers that prevented intermingling and reproduction between nearby populations.
This image accompanied NSF press release, "Reduced Oxygen Contributed To 'Great Dying.'" [See related image Here.]
Credit: Nicolle Rager Fuller, National Science Foundation, based on data from Robert Berner, Yale University, and from Raymond Huey and Peter Ward, University of Washington
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