Ancient air bubbles and Earth's Oxygen levels

Researchers have discovered ancient air bubbles trapped in inclusions found with rock salt. The chemical makeup of the air bubbles revealed that Earth's atmosphere was made up of roughly 11% oxygen 815 million years ago. This discovery puts an oxygenated atmosphere 200 million years ahead of when animals first began to appear. Scientist had previously thought oxygen didn't reach such high levels until approximately 600 million years ago at a similar time as when animals began to emerge. The new finding also puts the evolution of animals into question. There is now the question of whether or not the high oxygen levels had excelled the evolution of animals. Some scientists and universities are already disputing the evidence found claiming there must have a form of outside contamination within the samples.