Oxygen levels in the Earth's atmosphere are likely to havefluctuated wildly 1 billion years ago, creating conditions that could have accelerated the development of early animal life.
The Great Oxidation Event is believed to have started when oxygen first appeared in the atmosphere. The third stage happened around 400 million years ago.
It's not clear what happened during the second stage of the Neoproterozoic Era, which began about 1 billion years ago and ended around 500 million years ago.
Scientists want to know if there was anything special about the changes to oxygen levels in the Neoproterozoic Era. Is there a sudden increase in oxygen levels?
The fossils of animals that required oxygen have been found in rocks that are over 500 million years old.
The different forms of carbon were measured in limestone rocks taken from shallow seas.
As a result of the calculations, they have been able to produce a record of oxygen levels in the atmosphere over the last 1.5 billion years.
The lead scientist on the project said the findings gave a new perspective on how oxygen levels were changing on Earth.
The early Earth was devoid of atmospheric oxygen for 2 billion years. The Great Oxidation event happened when oxygen levels rose.
Scientists used to think that after the Great Oxidation event, oxygen levels were either low or high before the animals came along.
Oxygen levels were much more dynamic. There was a time when the ocean environment had high and low levels of oxygen.
Some life forms may have become extinct and new ones could emerge if the periodic change in the environment produced evolutionary pressures.
The areas of the ocean where oxygen levels were high enough to support early animal life forms were expanded by the oxygenated periods.
He said that ecological theory suggests that when a space is expanding and contracting it can support rapid changes to the diversity of life.
The extinction of some organisms could be caused by the environmental pressure on them when oxygen levels decline.
It would have taken plenty of time for the ecosystems to develop.
Science Advances contains the research.
More information: Alexander J. Krause, Extreme variability in atmospheric oxygen levels in the late Precambrian, Science Advances (2022). DOI: 10.1126/sciadv.abm8191. www.science.org/doi/10.1126/sciadv.abm8191 Journal information: Science Advances
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