Scientists in Africa have discovered what they believe are the first signs on Earth of a creature searching for food – nearly 2.1 billion years ago.
The previous earliest remnants known about, in the same country, were dated to 570m years ago.
The international team, led by scientists at the University of Poitiers in France, said the discovery raised new questions on the history of life.
Writing in the Proceedings of National Academy of Sciences journal, they said: “Was this biological innovation the prelude to more perfected forms of movement or an experiment cut short by the drastic drop in atmospheric oxygen rates which occurred approximately 2.083 billion years ago?”
Using X-ray analysis they found tubular burrowing tracks in sedimentary mud from organisms that may have been similar to colonial amoebae, they added.
The organisms cluster together when resources are scarce to form a type of slug that moves in search of a “more favourable” environment.
The findings showed that certain multi-cellular organisms in the primitive marine ecosystem were sophisticated enough to move through its mud, which was rich in organic matter, the team said.
“The more or less sinuous structures are tubular, of a generally consistent diameter of a few millimetres, and run through fine layers of sedimentary rock,” they added.
Additional reporting by SWNS