The fossils date back to almost 3.5 billion years ago and are strong evidence of the earliest life that existed on Earth.
An worldwide team of scientists has recently uncovered what they believe are the earliest animal fossil footprints on record, Phys.org reports. This is considered the earliest animal fossil footprint record. But they say the tracks probably belong to a bilaterian.
"The footprints are organised in two parallel rows, as expected if they were made by animals with paired appendages".
"It is important to know when the first appendages appeared, and in what animals, because this can tell us when and how animals began to change to the Earth in a particular way", Xiao said.
Still, this discovery means that paleontologists will have to revise their vision of how life developed in Earth's primordial oceans.
The Ediacaran-era (541- 635 million years ago) prints were found by researchers from Chinese Academy of Sciences' Nanjing Institute of Geology and Palaeontology and Virginia Tech in the United States during a study of tracks and burrows spotted at the Dengying Formation, a fossil-rich site near the Yangtze Gorges area of southern China.More news: Multi-state Salmonella outbreak connected to Walmart pre-cut melons
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That's largely because Ediacaran life hadn't yet evolved the kinds of hard bones and shells that fossilize easily, so scientists usually have to rely on trace fossils instead - burrows, tracks and other secondary evidence of their existence.
Previously, it was believed animals with pairs of legs capable of leaving such footprints first appeared during the "Cambrian Explosion" about 541 to 510 million years ago. "Arthropods and annelids, or their ancestors, are possibilities".
The trackways indicate a connection to burrowing, suggesting that whatever animal this was might have had a habit of digging into sediments and microbial mats.
The researchers, led by Zhe Chen and Shuhai Xiao, say it's highly likely the prints were produced by a bilaterian animal with paired appendages, but they know very little beyond that.