Scientists are getting closer to unlocking the secrets of oxygenation of the Earth’s biosphere -its oceans and atmosphere- with new research shows that shows that organisms like vascular plants may have appeared and evolved under lower oxygen conditions than previously thought.
Ariel Anbar, Arizona State biogeochemist, and an international team of scientists, using pioneering techniques at Arizona State University, have found that the appearance of large predatory fish as well as vascular plants approximately 400 million years ago coincided with an increase in oxygen, to levels comparable to those we experience today. If so, then animals from before that time appeared and evolved under markedly lower oxygen conditions than previously thought.
“There has been a lot of speculation over the years about whether or not oxygen in the atmosphere was steady or variable over the last 500 million years,” explained Anbar, who leads ASU’s Astrobiology Program. “This is the era during which animals and land plants emerged and flourished. So it’s a profound question in understanding the history of life. These new findings not only suggest that oxygen levels varied, but also that the variation had direct consequences for the evolution of complex life.”
Read the whole article here Oxygen! Its Evolution on Earth.