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Minuscule oxygen bubbles trapped for 1.6 billion years found in India

Fossilised bubbles and cyanobacterial tissue from 1.6 billion year old microbial phosphate mats from the Vindhyan Supergroup, Central India. Credits: Stefan Bengtson

A team of geologists have revealed the discovery of minuscule fossilised oxygen bubbles, created by microbes that evolved 1.6 billion years ago in shallow waters. 

You would need very good eyesight to catch a glimpse of this phenomenon! Imagine these minuscule bacteria, some of the first forms of life on Earth, leaving after them a chemical signature found and analysed 1.6 billion years later. These microbes are of particular interest: they were not only the first forms of life on Earth, but they also transformed our planet into a viable environment for the earliest plants and animals, and consequently, paved the way for life as we know it.

Some of these earliest microbes were cyanobacteria, which prosper in shallow water. These are photosynthesising bacteria, meaning that like plants, they draw some of their energy from the sun to synthesise their organic molecules. They thus produce oxygen via photosynthesis, and sometimes the oxygen remains trapped in the form of bubbles in the microbial mats. Geologist Therese Sallstedt and her team coming from the University of Southern Denmark, from the Swedish National History Museum and the University of Stockholm, found these signs of life embedded in fossilised sediments in India.

“We interpret them as  bubbles created in cyanobacterial biomats in shallow waters 1.6 billion years ago”, says the researcher, who published her works in the journal Geobiology.

Cyanobacteria changed the Earth’s surface in an irreversible manner, and were responsible for oxygenating the atmosphere. Simultaneously, they also formed sedimentary structures called stromatolites, which still exist on Earth.

Researchers are now suggesting that the cyanobacteria played an even more important role than was previously thought, creating phosphorites in shallow waters. This now provides scientists with a unique approach for studying the ecosystems of the past.