Prior to this discovery, it was suspected that animals with legs first appeared during this period, but no evidence had ever been found.
Researchers believe they may have been a type of arthropod - the family of animals with jointed limbs that includes insects and crustaceans, or something akin to a legged worm.
Recently, an worldwide research team reported discovering fossil footprints for animal appendages in the Ediacaran Period (about 635-541 million years ago) in China. The rocks they come from are dated between 551 million and 541 million years old.
As the Inquisitr previously reported, up until that historic event, which lasted for 20-25 million years and gave rise to most of the major animal groups on the planet, animal life on Earth was limited to simpler, single-celled or multicellular organisms.
The odd-looking prehistoric trackways show two rows of imprints that resemble a series of repeated footprints, the researchers said.
"They were probably made by millimeter-sized animals with bilateral appendages and can provide important insights into early bilaterian evolution and behaviors".
Prof Shuhai Xiao, a geobiologist at Virginia Tech University and senior author of the research, said the finding brings scientists closer to understanding what creatures were the first to evolve pairs of legs.
"This is considered the earliest animal fossil footprint record", the researchers wrote in the report.
"Arthropods and annelids, or their ancestors, are possibilities". The trackways also appear to be connected to burrows, suggesting the creatures periodically tunnelled down into the sediments, perhaps to mine oxygen and microbes as food. Maybe they were never preserved. "Late Ediacaran trackways produced by bilaterian animals with paired appendages". Researchers say that these prints were made by creatures with appendages and this discovery is proof that there were indeed animals with limbs in the Ediacaran period.
Highlights: Halep ends Muguruza hopes to reach final
Halep, who assured herself of retaining the No. 1 ranking with the victory, earned a fourth chance to win her first major title. She said she expected an intense match against Sharapova, and, in a way, it was - intensely straightforward and efficient.