520-million-year-old discovery in China leaves scientists stunned - Miniature brain and nerves

Scientists have discovered a rare, 520-million-year-old fossil with its internal organs fully preserved, which offers insights into the earliest ancestors of arthropods. The researchers at the University of Durham made the discovery in China and published their findings in the journal Nature. The fossil has been named Youti yuanshi, and is linked to modern-day animals like crabs, lobsters, spiders, insects and centipedes. Scientists say this fossil belonged to a larva and is extremely tiny. So scanning it needed complex technology. The team relied on advanced scanning technology to scan Youti yuanshi. They stated in a press release that 3D imaging of "the miniature brain regions, digestive glands, a primitive circulatory system and even traces of the nerves supplying the larva’s simple legs and eyes" was carried out.

A dream come

Dr Martin Smith of Durham University, the lead author of the study, described the discovery of the fossil as something he had dreamt of for a long time. “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,” he said. The fossil is currently at Yunnan University in China.

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He added that larvae are extremely fragile, which is why it was believed to be almost impossible to find a fossil. However, when the team came across this specimen, they were surprised since they had not only found a fossilised larva, but one with its organs fully intact. Smith said his jaw just dropped when he saw the structures preserved under its skin. "How could these intricate features have avoided decay and still be here to see half a billion years later?"