Three-and-a-half billion years is a long time — after all, humans have only been around for about 2.3 million years. But scientists working in Western Australia's geologically rich Pilbara region say they've found the world's oldest fossils -- tiny weblike patterns on sandstone that date back 3.49 billion years.
The fossils were likely left by bacteria similar to those now living, according to a paper presented last November at the annual meeting of the Geological Society of America in Charlotte, N.C. But evidence suggests that the ancient germs lived at a time when the earth lacked oxygen in its atmosphere -- and, in fact, may have produced oxygen that helped build our atmosphere.
“Studying this kind of past life is really about learning how the Earth got to be the way it is today,” Michael Tice, a geobiologist at Texas A&M University, told the Washington Post.
But Earth isn't the only planet on the scientists' radar. The research may aid in the search for fossils on other planets. NASA's Curiosity rover has instruments capable of detecting similar fossils in Martian rocks, according to U.S. News.
Despite their age, the fossils are in great shape.
"I can confidently say the structures we're working on cannot be found on older rocks — until now, there has been nothing that is this well preserved,' co-author Nora Noffke, associate professor of ocean, earth and atmospheric sciences at Old Dominion University, told U.S. News. "There are some [rocks] that are much older, but they experience metamorphosis -- anything that's on them has been overprinted and it's difficult to reconstruct what was there."
The Pilbara region has some of the world's oldest rocks and is popular with fossil hunters, according to the Washington Post.