Every now and then, our planet gives us a fossil so spectacular that we can’t help but be amazed. This is also the case with an almost perfectly preserved million-year-old larva.
Sometimes these fossils are the magnificent remains of creatures that trampled the earth with thunderous footsteps. Other times, they are just tiny particles that you might not even give a second glance at, but which contain the secrets of many species.
One such example is a million-year-old larva the size of a sesame seed discovered encased in stone in China. Hailing from the Cambrian period, about 520 million years ago, this larva represents an entirely new genus and species of euarthropod, and has been named Youti yuanshi.
A million-year-old larva was almost perfectly preserved
Such a small fragment of rock can be easily overlooked, but this remarkable fossil has been almost perfectly preserved, including its internal anatomy. The larva is an ancestor of the arthropods that populate our planet today, i.e. spiders, crabs and insects. That means it can give us information about the evolutionary history of these animals, information that very few fossils can reveal, points out Science Alert.
“When I dreamed of the fossil I’d most like to find, I always thought of an arthropod larva, because developmental data is so essential to understanding their evolution,” says paleontologist Martin Smith, of the University Durham (UK).
“But the larvae are so small and fragile that the chances of finding a fossilized one are practically zero, or so I thought! I already knew this simple worm-shaped fossil was something special, but when I saw the amazing structures preserved under its skin, I was amazed; how could these intricate features have avoided decay and still be visible after half a billion years?” asks the researcher.
Even the worm’s organs were preserved
The three-dimensional fossil was found in a shale rock known for its wealth of fossils called the Yu’anshan Formation. The larva was carefully extracted using acetic acid and then subjected to high-resolution scanning to be fully mapped and uncover anything that might be hidden inside.
Although only a few millimeters in size, the fossil is spectacularly detailed. Its exterior features textured skin, head and legs. Inside, X-ray computed tomography revealed the larva’s intact internal anatomy. This includes the brain, digestive glands, circulatory system and nervous system.
“It’s always interesting to see what’s inside a specimen using 3D imaging, but in this incredibly small larva, natural fossilization has achieved almost perfect preservation,” says geologist Katherine Dobson, from the University of Strathclyde (UK).
A million-year-old larva could help us understand life on Earth
Given the age of the larva and the fact that it represents a developmental stage in the life cycle of an arthropod rarely found in ancient fossils, scientists believe that Y. yuanshi can help us understand the early development and evolution of this highly successful phylum of the animal kingdom. The worm itself looks simple compared to the complex bodies of today’s arthropods, but hints of the animals that would later appear can be seen in its internal anatomy. For example, its protocerebrum (the worm’s brain region) foreshadows the more complex cranial anatomy that developed with the evolution of arthropods.
In addition, the circulatory and digestive anatomy of Y. yuanshi may be related to the later development of arthropod characteristics.
This early anatomy, the researchers say, highlights how arthropods diversified remarkably, developing the ability to specialize in various ecological environments and spread across the globe.
Although this unique fossil of Y. yuanshi is much smaller than a human palm, its discovery has major implications for understanding life on Earth.
The research was published in Nature.
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Source: www.descopera.ro
