They really are tiny. From the size of the burrows, scientists have worked out that these ancient creatures measured just 40 to 300 micrometers – about the width of a strand of human hair. They would have moved around the sediment, wiggling and leaving behind burrows as they go.
The thing that is really fascinating is their age. The burrows were fossilized during a period known as the Ediacaran-Cambrian transition (around 541 million years ago), an important turning point in evolutionary history. To give that some context: The first dinosaurs appeared around 230 million years ago during the Mesozoic Era, and modern Homo sapiens have only been around for the past 200,000 or so years.
"The evolutionary events during the Ediacaran-Cambrian transition are unparalleled in Earth history," said Garwood. "That's because current fossil records suggest that many animal groups alive today appeared in a really short time interval."
"Our discovery highlights an unexplored window for tracking animal evolution in deep time," Parry added.