Half-a-billion-year-old fossils reveal secrets of animal evolution

An international team of scientists has found evidence of complex life more than 500 million years old a discovery that will likely shake up the current understanding of how animals evolved.
By Delila James | Sep 13, 2017
An international team of scientists has found evidence of complex life more than 500 million years old a discovery that will likely shake up the current understanding of how animals evolved.

The discovery is detailed in the journal Nature Ecology & Evolution.

The team discovered the trace fossils the tracks and burrows left behind by living organisms in sediment located in western Brazil. The creatures that made the burrows, which measure between 50 and 600 microns in diameter, were about the size of a human hair.

"This is an especially exciting find due to the age of the rocks these fossils are found in rock layers which actually pre-date the oldest fossils of complex animals at least that is what all current fossil records would suggest," said co-author Dr. Russell Garwood of the University of Manchester's School of Earth and Environmental Sciences, in a statement.

The newly discovered trace fossils, which date back to the geological period known as the Ediacaran-Cambrian transition, represent some of the first organisms capable of self-propelled movement.

"The evolutionary events during the Ediacaran-Cambrian transition are unparalleled in Earth history," explained Garwood. "That's because current fossil records suggest that many animal groups alive today appeared in a really short time interval."

The researchers think the burrows were created by nematode-like creatures that used an undulating-type of locomotion to move around, similar to a modern roundworm.

"Our new fossils show that complex animals with muscle control were around approximately 550 million years ago, and they may have been overlooked previously because they are so tiny," said lead author Luke Parry from the University of Bristol.

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