Oxygen catastrophe
From Tardis Wiki, the free Doctor Who reference
The oxygen catastrophe occurred on Earth during the Precambrian, when oxygen was added to the planet's atmosphere by microscopic life through photosynthesis, making it possible for larger, more complex life to evolve. The oxygen catastrophe wiped out much of the existing life on Earth that could not tolerate the new oxygen-rich conditions. (PROSE: Prehistory Repeating Itself [+]Loading...["Prehistory Repeating Itself (feature)"])
