'Earliest animal fossil footprints discovered in China'


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.

A group of animal footprint fossils thought to be more than 541 million years old has been found in central China's Hubei Province, the US-based scientific journal Science Advances said on Wednesday.

"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.

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However, the fossil record of animal appendages confirms that their evolutionary ancestry was rooted in the Ediacaran Period, the researchers noted.

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.

'At least three living groups of animals have paired appendages (represented by arthropods such as bumble bees, annelids such as bristle worms, and tetrapods such as humans)', said Dr Chen.

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.