Researchers have made the astonishing discovery of life forms that actually pre-date oxygen on Earth.
Scientists from the University of Cincinnati have presented a number of fossil samples which date back to around 2.5 billion years ago.
The fossils show microscopic bacterium that survived during a time when Earth’s oxygen levels were less than one-thousandth of one percent of what they are today.
Despite there being practically no air to breathe, these sulphur-oxidising were still able to survive during this tumultuous period in Earth’s 4.5 billion year history.
They would have been considered giants when put alongside modern bacteria. They’re spherical shaped, smooth walled and show some similarities to the single-celled bacteria we’ve found congregating around sulphur vents deep beneath the ocean.
Andrew Czaja, UC assistant professor of geology explains that these will now officially take the record of being the “oldest reported fossil sulfur bacteria to date,”
“This discovery is helping us reveal a diversity of life and ecosystems that existed just prior to the Great Oxidation Event, a time of major atmospheric evolution.” explains Czaja.
Czaja has published his findings in the scientific journal Geology along with fellow colleagues Nicolas Beukes from the University of Johannesburg and Jeffrey Osterhout, a recently graduated master’s student from UC’s department of geology.
To put this discovery into some context many scientists believe that organisms did exist on a pre-oxygen Earth but until now there has been no clear evidence to support it.
“These bacteria existed two billion years before plants and trees, which evolved about 450 million years ago. We discovered these microfossils preserved in a layer of hard silica-rich rock called chert located within the Kaapvaal craton of South Africa.” explains Czaja.