New research identifies a previously overlooked global event which changed the course of the evolution of life in the oceans. It coincided with a rise in calcium carbonate-secreting plankton and their subsequent deposition on the ocean floor.
The new study is the first to distinguish between bodies of water with low and high levels of oxygen. It shows that poorly oxygenated waters did not support the complex life that evolved immediately prior to the Cambrian period, suggesting the presence of oxygen was a key factor in the appearance of these animals.
