There is a geological period called the Cambrian, about 540 million years ago to 490 million years ago.
If the overlord of the Cretaceous period was the Rex Tyrannosaurus, then the overlord of the Cambrian period is none other than the odd shrimp.
Odd shrimp are not real shrimps, they are an extinct invertebrate.
The odd shrimp is about 2 meters long, and in front of its mouth there are two powerful, huge gripping pliers, which are equivalent to the large long legs of humans.
The pliers have many barb-like spikes, probably used to capture and devour prey.
The average size of animals in the Cambrian period was only a few millimeters to a few centimeters, and in contrast, the odd shrimp were well-deserved trolls.
Typical odd shrimp are divided into three genera, namely Canadian odd shrimp, double-limbed odd worm, and Cambrian dried worm.
Canadian odd shrimp
Among them, the Canadian odd shrimp has a pair of huge compound eyes with stalks, a pair of segmented giant forelimbs, a beautiful large tail fan and a long tail fork.
Odd shrimp are high-definition compound eyes that contain at least 16,000 hexagonal crystal bodies per eye. Like the eyes of many insects today, it is also a plus enhanced version. It is estimated that if you want to eat it, it can be counted as a traditional Chinese medicine.
As a large predator in the Cambrian ocean, it is not good at walking, but it is a master swimmer.
Its findings show that a pyramidal ecosystem, commonly known as food chain relationships, had been established between Cambrian organisms.
From left to right, they are the two-limbed monster worm and the Cambrian worm
In the Chengjiang region of Yunnan, China, it is common to have bilimbs.
As the attack ability of some carnivores in the Cambrian ocean is further improved, one class of arthropods will defend against foreign attacks by building calcified exoskeletons, and this class of arthropods is trilobites, which are important taxa in cambrian oceans.
Because the trilobite exoskeleton is very suitable for preservation as a fossil, this makes it a common fossil in the Cambrian strata, and the Cambrian is also exaggerated as the trilobite era.
Small oil ctenophores
Currently, we know that trilobites are 1 mm to 1 m long. From front to back, it can be divided into three parts: the shield-shaped head (head armor), the thorax (which can reach up to 30 segments) and the tail armor (tail plate). There are about 10,000 species of trilobites. Most trilobites do not actively attack other animals because they are not good at swimming and are slow to move.
Lederliki worm
Usually they live on the seabed, mainly on lower plants such as seaweed, or feed on small animals and carcasses. And its biggest natural enemy is the cambrian ocean overlord mentioned above- the odd shrimp.
The mystery of the extinction of the odd shrimp
Like the dinosaurs, the odd shrimp did not escape the fate of extinction.
The latest odd shrimp to be discovered is more than 440 million years ago, and the race has existed for less than 100 million years. How did the odd shrimp become extinct? It's still a mystery.
However, scientists speculate that "later the size of marine life has also become larger, some even larger than the odd shrimp." This advantage of the odd shrimp is gone, there is not enough food to meet its survival needs, and it may be starved to death. ”
Darwin's Confusion
Before the Cambrian Period, the species and number of organisms on the earth were very small, so it was also known as the "Cryptozoic Universe".
With the exception of some algae fossils produced in the ocean, animal fossils are pitifully rare.
It was from the early Cambrian period of millions of years that colorful and colorful creatures began to appear in the oceans of the world.
The vast majority of invertebrate ancestors today, as well as the ancestors of vertebrates, appeared in just over 20 million years. This is the famous "Cambrian explosion of life" in biology. Thus began the Eminence.
What led to such a landmark event in biological evolution?
Back 160 years ago, Darwin, the author of On the Origin of Species, was just as confused as you are. This "simultaneous" and "sudden" appearance of numerous invertebrate fossils over tens of millions of years contradicts the theory of evolution.
This is also due to the incompleteness of the fossil record, and a large number of fossils are destroyed by geological processes.
Editor: Shen Xiangsha
Editor-in-charge: Gu Jun