The discovery of a 5-eyed shrimp-like creature that lived about 520 million years ago could end a lengthy debate about the evolution of the most common animals on Earth.
Arthropods, from lobsters and crabs to spiders and spiders, make up about 80% of all living animals today and are characterized by their hard exoskeletons.
But their evolution has long remained a mystery, because their ancient ancestors carried many features that modern humans do not have.
Enter Kylinxia zhangi, a shrimp-like creature preserved in fossils found in Yunnan province, China – a discovery that researchers now think may be an important “missing link”; during the evolution of arthropods.
Like arthropods today, Kylinxia has a hard shell, segmented body and jointed legs.
But this ancient creature also shares common traits with older animals, prompting researchers to name it “Kylin”, a creature in traditional Chinese mythology with properties from many. animals.
The first is those eyes – three smaller ones in a row on the head, with two larger ones right behind.
It sounds strange, but it’s a trait scientists have seen before, in an ancient creature called Opabinia, known as the “strange wonder”.
Kylinxia’s two spiky front appendages are reminiscent of another creature thought to be the ancestor of arthropods: Anomalocaris, the researchers said.
– ‘Evolutionary gap’ –
While both are thought to be precursors to modern arthropods, an evolutionary flaw in the fossil record makes it difficult to prove – until this week.
“Kylinxia represents an important transitional fossil predicted by Darwin’s theory of evolution,” said Han Zeng, the first author of the study published in the journal Nature on Wednesday.
Zeng, a researcher at the Nanjing Institute of Geology and Paleontology (NIGPAS), said: “It narrows the evolutionary gap from Anomalocaris to actual arthropods and forms a ‘missing link’. important in the origin of arthropods.
In fact, when the fossil’s first was revealed, only its foreleg was visible and the researchers assumed it was another specimen of Anomalocaris, said Diying Huang, professor at NIGPAS .
Huang, study author, told AFP: “It looked odd, like an aomalocaris frontal appendage attached to the body of a common arthropod.
“After careful preparation … I knew it was a new and very important arthropod.”
Part of the value of Kylinxia lies in other details often preserved in fossils.
“The Kylinxia fossils exhibit a delicate anatomical structure,” said Fangchen Zhao, co-author of the study.
“For example, the nervous tissue, the eyes, and the digestive system – these are soft body parts that we normally cannot see in conventional fossils.”
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