Paleontologists find world's oldest fossil

March 1 (UPI) -- Scientists have discovered the world's oldest fossil, the remains of a microorganism that lived between 3.7 billion and 4.3 billion years ago. Earth itself is believed to have formed just 4.5 billion years ago.

The signature of the iron-eating bacteria -- its tiny filaments and tubes -- was found encased in a piece of quartz excavated from the Nuvvuagittuq Supracrustal Belt in Quebec, Canada.

Scientists described their discovery in the journal Nature.

"Our discovery supports the idea that life emerged from hot, seafloor vents shortly after planet Earth formed," Matthew Dodd, a PhD student at University College London, said in a news release. "This speedy appearance of life on Earth fits with other evidence of recently discovered 3,700 million year old sedimentary mounds that were shaped by microorganisms."

Prior to the latest discovery, the oldest known microfossil was a fragment of mineralized bacteria found in Western Australia and dated at 3.4 billion years old. But some scientists suggested the fossil was a non-biological anomaly in the rock.

Researchers analyzed the newly discovered piece of quartz to determine whether the mineralized tube structures could have been formed by temperature or pressure changes. They determined a geochemical explanation for the filaments was highly unlikely.

The fossil microstructures are made of hematite, a type of iron oxide, and perfectly resembles the branch-like pattern of modern bacterial species found near hydrothermal vents.

"This discovery helps us piece together the history of our planet and the remarkable life on it, and will help to identify traces of life elsewhere in the universe," added study leader Dominic Papineau.

"These discoveries demonstrate life developed on Earth at a time when Mars and Earth had liquid water at their surfaces, posing exciting questions for extra-terrestrial life," Dodd concluded. "Therefore, we expect to find evidence for past life on Mars 4,000 million years ago, or if not, Earth may have been a special exception."