In a study from Earth and Planetary Science Letters, scientists discovered that the Earth's first oxygen-producing bacteria existed 200 million years earlier than originally hypothesized, according to Gizmodo. The bacteria were found when the scientists noticed iron-rich layers present in sediments stored in ocean floors, a commonly known indicator of oxygen, according to Science News.
The source of the oxygen is cyanobacteria, tiny green microbes that were responsible for the earliest forms of photosynthesis, a process used by plants to capture sunlight and use it for energy.
Cyanobacteria reportedly took off 2.3 billion years ago and began releasing large amounts of oxygen into the atmosphere. While some anaerobic microbes suffered due to intolerance, the release of oxygen was beneficial for most multicellular life forms - geologists are already referring to the event as a turning point in the timeline of Earth.
The study confirms previous studies that have also pointed to cyanobacteria as the starting point of oxygen in the Earth's atmosphere, according to Scientific American.
"What it looks like is that oxygen was first produced somewhere around 2.7 billion to 2.8 billon years ago," said geochemist Dick Holland. "It took up residence in atmosphere around 2.45 billion years ago. It looks as if there's a significant time interval between the appearance of oxygen-producing organisms and the actual oxygenation of the atmosphere."
