Scientists have directly measured the air that was breathed by Earth’s first animals for the first time
The discovery of an atmospheric time capsule has allowed scientists to directly measure the air breathed by the first animals. A team of international researchers, including geologists from the University of Aberdeen, made the discovery while analysing samples of halite ie rock salt – dated 815 million years old. The halite was found to contain traces of trapped atmospheric gas, from which measurements of oxygen were taken. The analysis found that the percentage of oxygen present in the atmosphere 815 million years ago was enough for animals to flourish. Some studies have suggested that the required level of oxygen would only have been present much later in the Earth’s history.
Professor Parnell said: “We crushed samples of halite that were preserved in a drill core in Australia and removed the gases trapped in the salt crystals, which allowed us to measure the percentage of oxygen in the gases trapped 815 million years ago… We measured the oxygen at 10.3 to 13.4% of the atmosphere, which would have been enough for animals to flourish. In comparison, the oxygen content of modern Earth’s atmosphere is 20.9%….What is especially significant in this study is that we actually discovered a real atmosphere sample, where previous estimates have been made using indirect modelling methods.”
Dr Blamey, who led the study, said the measurement was made possible by an international collaboration involving scientists from the UK, US, Canada, France, Australia and China. “This brought together expertise in technology, ancient rocks and the evolution of life, and built on years of experience crushing rocks exploring for gold, oil and gas,” he said. http://www.abdn.ac.uk/news/9456/
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