The oldest fossils yet known—an estimated 3.7 billion years old—were announced Wednesday, pushing back evidence of life on Earth by about 220 million years. These remains of ancient microbes were found in Greenland after they were exposed by melting ice—something that may become more common as the planet warms.
The fossils are known as stromatolites and are the evidence of ancient water-based bacterial colonies, which cemented sediments together into distinctive layers with carbonate. Before this new discovery, the oldest known fossils were 3.48-billion-year-old stromatolites found in Western Australia.
Published in Nature and led by the University of Wollongong’s Professor Allen Nutman, the fossils were found in the world’s oldest sedimentary rocks, in the Isua Greenstone Belt, along the edge of Greenland’s ice cap.
Co-author Martin Van Kranendonk, director of the Australian Centre for Astrobiology, says the newly exposed outcrops in Greenland offered a unique opportunity to find the fossils.
“It points to a rapid emergence of life on Earth and supports the search for life in similarly ancient rocks on Mars,” Van Kranendonk said in a statement.
This week’s discovery is another reminder of the rich trove of ancient secrets that are likely to become exposed as glaciers, permafrost, and sea ice melt in a warming world.
Photo credit: NASA/Saskia Madlener