A”shrimp” 500 million years ago was discovered for the first time! Like this
Kirin shrimp fossil. Photo courtesy Zeng Han
The unicorn is a beast in ancient Chinese mythology. According to legend, its body combines the characteristics of a variety of animals, including lion head, antlers, tiger eyes, moose body, dragon scales, and ox tail. One. A few days ago,”Nature” magazine recently reported that a strange-looking fossil discovered more than 500 million years ago by scientists at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, is called”unicorn shrimp.”
Why is it called”Kirin Shrimp”?
Where did the researchers find it?
What role does it play in the evolution of life?
Where is its scientific significance?
Recovery map of unicorn shrimp. Photo courtesy Huang Diying
Life has gone through a long history of about 4 billion years on earth. However, it was not until the Cambrian era more than 500 million years ago that complex and diverse life suddenly appeared on the earth. This milestone The major life evolution event of, known as”Cambrian Explosion“.
However, since Darwin, the”Cambrian Explosion” has been a major scientific mystery that plagued the scientific community. Darwin specifically mentioned in his”Origin of Species” that the sudden appearance of complex animals in the Cambrian was a huge challenge to the theory of evolution.
However, in 1984, the”Chengjiang Fauna” discovered in Yunnan by scientists from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences further highlighted the suddenness of the”Cambrian Outbreak” and brought”Darwin’s Confusion” pushed to the top. Because the discovery of fossils in the Chengjiang fauna shows that, including vertebrates, almost all modern animal phyla appeared 520 million years ago.
However, Darwin’s theory of evolution also proposed a way to solve the mystery of the”Cambrian explosion”, that is, scientists need to find the transitional ancestor fossils of the animal phylum origin.
Among the Chengjiang fauna, the most diverse is the arthropod, known as the”Cambrian The trilobites and prawns of the “star” are all arthropods. It is not an exaggeration to say that arthropods have been one of the most successful animals on earth since the great outbreak of the Cambrian.
Nowadays, the butterflies, crabs, centipedes and spiders that we know well are all arthropods. They have the same thing as a segmented body and appendages. It can be said that arthropods are the animals with the largest number of individuals on the earth today. They account for about 80%of the species diversity in the animal kingdom. They are found in various environments such as sea, land and air.
So, how did arthropods evolve? What did their ancestors look like? This is a major problem in biological evolution, which has plagued generations of scientists for more than 100 years. In the Chengjiang Biota, the abundant arthropod fossils have become one of the”bell-resolving stones” for”Darwin’s puzzle”.
This time, the Cambrian outbreak research team led by researcher Zhu Maoyan found the key fossil”Zhang’s unicorn shrimp” to answer the”mystery of the origin of arthropods” in the Chengjiang fauna.
The reason why it is called”Kirin Shrimp” is because it is like the”four different” auspicious beasts-unicorns in Chinese traditional mythology, and its body is embedded with various animal morphological characteristics.
“Unicorn Shrimp” is a shrimp-shaped, with five eyes, and possessed the giant predatory animal in the ocean at that time”Odd Shrimp“Big tongs” for predation, as well as the many characteristics of arthropods (such as ubiquitous mosquitoes, insects, shrimps, and crabs) that we now know.
Recovery of unicorn shrimp. Courtesy of Huang Diying Figure
In the Chengjiang fauna, the prawn is considered to be the ancestor type of arthropods. It is the top predator with a body length of up to two meters. However, the morphological difference between the prawn and the true arthropod is huge. , There is an evolutionary gap that is difficult to bridge between the two. This gap has become a key missing link in exploring the”mystery of the origin of arthropods”.
The”unicorn shrimp” discovered this time has its head embedded It combines the morphological structure of the ancestor type of arthropods, including the Cambrian monster-the unique five eyes of the Opabin sea scorpion, and the predatory appendages of the Cambrian giant top predator-the prawn. However, the body has Obvious features of true arthropods, such as hardened epidermis, healed head shell, multi-segmented torso and segmented legs.
Among the fossils of”Zhang’s unicorn shrimp” discovered this time, the smallest Like dried shrimps, the largest one is 7cm long.
The research team used a variety of technical methods to carry out detailed comparative anatomical studies on the fossil”unicorn shrimp”. The world’s other Cambrian periods have been accumulated over the years. Based on the fossil research data, combined with the unique chimeric morphology and evolutionary developmental biology analysis of the”kylin shrimp”, the homology of the first pair of appendages between the strange shrimp and the true arthropod was demonstrated.
Researchers reconstructed the pedigree and calculated a new model that reversed the evolutionary relationship of early arthropods and the morphological changes of appendages. The results showed that the evolutionary position of the”unicorn shrimp” was between the strange shrimp and other true arthropods, and was located in the true arthropod. The root.
The”unicorn shrimp” represents an important transitional fossil predicted by Darwin’s theory of evolution. It bridges the evolution from the strange shrimp to the true arthropod and fills in the key missing link in the origin of arthropods , Adds a powerful fossil evidence to the theory of biological evolution.
After several generations of scientists, people have gained a lot of important understanding of the mystery of the origin of animals. However, this is far from the end. In the evolution of life There are still many”mysteries” waiting for us to uncover in the process.