"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", the Chinese and American team led by Dr Shuhai Xiao, from Virginia Tech in the United States, wrote in the journal Science Advances.
According to the team, the animal appeared to have paused time to time as the footprints were connected to burrows. But what they can say, with reasonable certainty, is that the tracks probably belong to a bilaterian.
This is a group of animals characterised by having paired appendages - in this case, perhaps, paired legs.
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.
"Previously identified footprints are between 540 and 530 million years old", Dr Zhe Chen from the Nanjing Institute of Geology and Palaeontologytold MailOnline. Today, these creatures are spread throughout the Earth and are among the most diverse forms of animal life on the planet, notes the report.
"Animals use their appendages to move around, to build their homes, to fight, to feed, and sometimes to help mate", Virginia Tech University geobiologist and lead study author Shuhai Xiao told the Guardian. This means that the mystery animal might have periodically dug into the ocean floor's sediments and microbial matts, possibly to mine for oxygen and food, the researchers said.
He also said that arthropods and annelids or their ancestors are possible. The fossil of the animal has not been found or maybe it never got preserved. Well, the team has it narrowed down to a bilaterian animal - a creature with bilateral symmetry, that has a head at one end and the back end at the other, as well as a symmetrical right and left side, Live Science explains.