Geologists analyse air sample from 815-million-year-old rock salt sample
Scientists have for the first time measured the air breathed by planet Earth's earliest animals.
A team of researchers - including geologists from the University of Aberdeen - made the discovery of an "atmospheric time capsule" while analysing samples of 815-million-year-old halite, more commonly known as rock salt.
The halite was found to contain traces of trapped atmospheric gas including oxygen.
Analysis published in the Geology journal found the percentage of oxygen present in the atmosphere at the time was enough for animals to flourish.
Professor John Parnell, from the University of Aberdeen's school of geosciences, took part in the study led by Dr Nigel Blamey from New Mexico Tech and a team of international researchers.
Prof Parnell said: "With this study, the oxygen in the air that allowed the earliest animals to breathe has been measured directly for the first time.
"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.
"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.
"We had a good idea about how to get at the ancient air and it's very pleasing that our hunch has paid off."
Dr Blamey said: "This (study) 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."
The study was made possible by an international collaboration involving scientists from the UK, US, Canada, France, Australia and China.