Every now and again, our planet produces amazing fossils that leave you gaping in wonder.
Sometimes these fossils are majestic relics that once thundered across the Earth’s surface. Sometimes they are mere specks of dust and particles that we may never see again, but which hold countless secrets within.
The sesame-seed-sized fossilized caterpillar, found trapped in rock in China, lived during the Cambrian period around 520 million years ago and represents an entirely new genus and species. Euarthropods It is called Yuti Yuanxi.
Such a tiny rock would be easily overlooked, but this incredible fossil is almost perfectly preserved with all of its internal structures intact, and it represents the ancestor of arthropods like spiders, crabs, and insects that live on Earth today, meaning it can tell us more about the evolutionary history of these animals than even the tiniest of fossils can reveal.
“When I was daydreaming about the fossils I would most like to discover, I always thought about arthropod larvae, because developmental data are so important for understanding their evolution.” Paleontologist Martin Smith says: of Durham University in the UK.
“But because larvae are so tiny and fragile, I thought the chances of finding a fossilised larva were virtually zero. I already knew this simple, bug-like fossil was special, but when I saw the incredible structures preserved under the skin, my jaw just dropped. How could these intricate features have escaped decay and still be here after 500 million years?”
The three-dimensional fossils were found in shale. It is known to be especially rich in fossils. The rocks, called the Yuanshan Formation, were carefully extracted using acetic acid, then imaged in their entirety through high-resolution scans – and maybe even offering a glimpse into what lies within.
Though only a few millimeters in size, the fossil itself is remarkably detailed: on the outside, it has textured skin, a head, and legs. On the inside, X-ray computed tomography revealed that the larva’s internal structures are still intact, including its brain, digestive glands, circulatory system, and nervous system.
“It’s always interesting to see inside a sample using 3D imaging.” “The continental shelf is a very large area,” says geologist Katherine Dobson. “However, this incredibly tiny larva has achieved near-perfect preservation through natural fossilisation,” say researchers from the University of Strathclyde in the UK.
Because the larvae are so ancient and represent a developmental stage in the arthropod life cycle that is rarely seen in ancient fossils, scientists Y. Motoishi It helps us learn about the early development and evolution of this highly successful phylum in the animal kingdom.
Although the worm itself looks simple compared with the complex arthropod bodies of today, its internal structure shows hints of animals that came later: for example, the worm’s brain region, the protocerebrum, foreshadows the more complex cranial structures that developed as arthropods evolved.
In addition, Y. MotoishiThe structure of the circulatory and digestive systems of these animals may be related to the subsequent development of arthropod characteristics.
According to the researchers, this early anatomy highlights how arthropods have become so spectacularly diverse, specializing in a wide range of ecological environments and developing the ability to thrive across the planet.
This single Y. Motoishi Although the fossil is small enough to fit in the palm of your hand, its discovery has major implications for our understanding of life on Earth.
This study Nature.
