A collection of short wiggly structures discovered in ancient rocks could be the earliest fossilised traces of organisms able to move themselves, scientists say.
If scientists are correct, the 2.1bn-year-old structures point to an earlier origin than generally thought for eukaryotes – cells with a membrane-bound nucleus and which make up plants, animals and fungi – previouslybelieved to have first emerged about 1.8bn years ago. It also pushes back the earliest evidence of self-propelled movement of eukaryotes by 1.5bn years – scooping the title from far younger multicellular lifeforms – and would be the first clear signs of motility for any type of organism.
“The question is: is this the first evidence of locomotion in some sort of complex living organism, and if it is, why is it that it took about 1,500m years before we start to see similar things in abundance in the geological record?” said Dr Ernest Chi Fru from Cardiff University, the co-author of the research. “Was it an experiment in locomotion that failed?”
Writing in the Proceedings of the National Academy of Sciences, the international team of researchers reveal how they used imaging techniques to probe what they describe as “string-shaped structures” found in a deposit of black shale – sedimentary rock that formed from a muddy marine bed.
Found in Gabon, Africa, in what is called the Francevillian Formation, and dated at about 2.1bn years old, the rocks have previously – and controversially – been reported to contain the earliest signs of multicellular life.
Now researchers say the rocks also contain the earliest evidence of locomotion: a host of structures of up to 6mm across and up to 170mm in length, some of which are intertwined, with rounded ends. While some run horizontally through the rock, others bend upwards.
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