That leaves a mystery about what kind of animal left the tracks.
They are often assumed to have appeared and radiated suddenly during the so-called "Cambrian Explosion" about 541 to 510 million years ago, but scientists now tend to consider that their evolutionary ancestry was rooted in the Ediacaran Period.
"We do not know exactly what animals made these footprints, other than that the animals must have been bilaterally symmetric because they had paired appendages", study co-author Shuhai Xiao, a geobiologist from Virginia Tech, told the Independent.
The Chinese and American team led by Dr Shuhai Xiao, from Virginia Tech in the USA, wrote in the journal Science Advances: "The irregular arrangement of tracks in the trackways may be taken as evidence that the movement of their trace maker's appendages was poorly coordinated and is distinct from the highly coordinated metachronal (wave-like) rhythm typical of modern arthropods".
"Unless the animal died and [was] preserved next to its footprints, it is hard to say with confidence who made the footprints". The research was published in Science Advances on June 6, 2018.
The 550-million-year-old tracks measure only a few millimetres in width, and consist of two rows of imprints arranged in what the researchers describe as a "poorly organised series or repeated groups", which could be due to variations in gait, pace, or interactions with the surface of what was once an ancient riverbed.
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This is a group of animals characterised by having paired appendages - in this case, perhaps, paired legs. This early evidence of limbed critters is important for scientists, he added, as it can help us understand their evolution.
These legs raised the animal's body above the sediment it was moving across.
The researchers speculate that the same creature left both the tracks and the burrows, suggesting an animal that scurried and tunneled its way across the ground.
Also, the trackways appear to be connected to burrows, suggesting that the animals may have periodically dug into sediments and microbial mats, perhaps to mine oxygen and food.
An worldwide research team discovered the fossil tracks in China dating back to the Ediacaran Period, just before the Cambrian Explosion when life on Earth increased rapidly.
"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)".