A tiny worm that lived around half a billion years ago has been found almost perfectly preserved following scans at an Oxfordshire site.
Discovered in China, the remains of the larva has almost intact internal organs, making this an exceptionally rare find.
Scientist from Durham University were able to generate 3D images of the specimen which is about the size of a poppy seed using advanced scanning techniques at the Diamond Light Source facility in Harwell.
These scans uncovered several internal organs beneath the worm's skin that have remained intact for half a billion years.
This includes parts of the brain, digestive glands, a primitive circulation system, and traces of nerves in the larva's legs and eyes.
Durham University's Dr Martin Smith, who led the research, described the finding as "something special", saying usually, the chances of finding fossils of such tiny, fragile creatures are "practically zero".
Named Youti yuanshi, the larvae are around 520 million years old, dating to a time when a large diversity of life began to emerge on Earth, including various major animal groups still in existence today.
Researchers say the prehistoric creature “provides key clues” into how modern arthropods - a group that includes insects, spiders, crabs, and centipedes - evolved from worm-like ancestors.
Dr Smith said: “When I used to daydream about the one fossil I’d most like to discover, I’d always be thinking of an arthropod larva, because developmental data are just so central to understanding their evolution.
“But larvae are so tiny and fragile, the chances of finding one fossilised are practically zero – or so I thought.
“I already knew that this simple worm-like fossil was something special, but when I saw the amazing structures preserved under its skin, my jaw just dropped – how could these intricate features have avoided decay and still be here to see half a billion years later?”
The ancient creature is offering scientists insights into the evolutionary journey from simple worm-like organisms to the complex arthropods we know today, including butterflies, beetles, and centipedes.
A primitive structure in the brain region known as a protocerebrum was observed in the larva.
The presence of this precursor to the more sophisticated arthropod brain shows these early arthropod-relatives were much more advanced than previously thought, the researchers said.
Dr Katherine Dobson, of the University of Strathclyde, said: “It’s always interesting to see what’s inside a sample using 3D imaging, but in this incredible tiny larva, natural fossilisation has achieved almost perfect preservation.”
The research is published in the journal Nature.
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