Plants initiated evolutionary drama of Earth's oxygenation

Last Updated: Sat, Oct 09, 2010 09:10 hrs

An international team of scientists has taken a major step toward unlocking the secrets of oxygenation of the Earth's oceans and atmosphere.




"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 Ariel Anbar, who led ASU's Astrobiology Program.

"These new findings not only suggest that oxygen levels varied, but also that the variation had direct consequences for the evolution of complex life," said Anbar.

The study involved measuring the relative amounts of different isotopes of the element molybdenum in rocks called "black shales".

These rocks are formed from ancient ocean sediments.

The data Dahl obtained at ASU revealed that there were at least two stages of oxygenation during the Phanerozoic, separated by the oxygenation event 400 million years ago.



When that happens, the organic carbon - produced by photosynthesis - is not available for reaction with oxygen. The consequence is a rise in the amount of oxygen in the environment.


The finding were published Proceedings of the National Academy of Sciences (PNAS). (ANI)