After eating all kinds of delicious shrimp, you may not think that this kind of "shrimp" used to be the "overlord" of the earth.

SME Press: Under the turbine of the changing times, after the cruel natural environment and strict survival rules, human beings are now at the top of the food chain. But before that, what kind of creatures can sit on the throne of "the overlord of the earth"? Many people know that dinosaurs are among them, but a "strange shrimp" with four species characteristics, as the first "overlord" on earth, is little known.

Speaking of the overlord of the earth, most people think of dinosaurs first. When it comes to shrimp, your first thought must be eating, right?

There are too many kinds of shrimp. We don't need to look up information, just count what we usually eat and we can come up with many kinds. As for cooking methods, there are sashimi, braised in oil, steamed, stir-fried, braised in brown sauce and braised in cheese, and any one of them can make your mouth water.

However, if you treat shrimp as a dish now, you will never think that there was once an extremely bullish shrimp, which was once the overlord of the earth, and this shrimp dominated much earlier than dinosaurs.

Let's just say, you may immediately think that in ancient times, before humans and dinosaurs appeared, a Pippi shrimp was arrogant in the ocean. Well (expressing hesitation, etc.) ... it seems a little hard to say.

But there is actually a kind of "shrimp", which was so brilliant at the beginning.

However, this "shrimp" is not another "shrimp". Not only does it look nothing like the shrimp we usually see, but it has nothing to do with blood. It is the first "overlord" on the earth-a carnivore of Precambrian more than 500 million years ago-strange shrimp.

Speaking of the discovery and naming of exotic shrimp, there used to be a modest joke.

The first kiwi shrimp specimen appeared in Canada. 1892, the famous Canadian paleontologist Whitway named the new species found in CAMBRIAN fossils. The creatures in fossils are arthropods that look like shrimp, but they only have bodies and no heads. This is so weird!

But it looks like shrimp, which Whitway thinks is shrimp. So he named the creature in this fossil "Anomalocaris", which translated into Chinese as "strange shrimp". The name is really straightforward. The Chinese translation of the name simplifies the translation and calls this species "strange shrimp".

Many years later, scientists never stopped studying the Cambrian biota, but failed to make more new discoveries on this strange shrimp. Until 198 1 years ago, Professor whittington of Cambridge University discovered something that shocked him: in an incompletely preserved fossil, he found an animal with four species marks at the same time!

At the same time, the animals in this animal fossil gather the bodies of arthropods Sidney worm, sea cucumber dragworm, jellyfish Peto worm and strange shrimp discovered and named in these years. Four completely different animals are spliced into one animal? !

1992, the first complete fossil of this species was finally unearthed in Maotianshan Mountain, Chengjiang, Yunnan Province in Greater China. Through repeated comparisons, scientists determined the true face of this species. The four creatures discovered before are really just different parts of this species' body, and the "strange shrimp" fossils first discovered are actually just the forelimbs of this species.

Maybe it's because this species looks really strange. When scientists finally named it, they continued to use the name Qixia.

The discovery process of kiwi shrimp can be called "bumpy", but scientists can't be blamed. There are special reasons for this.

You may have heard of another nickname of CAMBRIAN: trilobite period. The Cambrian, which gave birth to countless species, was "exclusively named" by trilobites because of the number of fossils unearthed by trilobites.

As a rare creature that evolved into an exoskeleton at that time, trilobites are more likely to form fossils because their remains are protected by exoskeletons and are not easily eroded by microorganisms. At present, trilobite fossils are still the largest category of CAMBRIAN fossils.

In contrast, most of the creatures of the same period have no skeleton structure at all, so it is difficult to produce fossils or fossils are incomplete.

Strange shrimp should be regarded as a typical case.

Its structure is very strange. Without spine and exoskeleton, the body is soft and covered with meat. But there are also hard structures such as forelimbs and mouthparts. This strange shrimp has been excavated many times, but it has not been recognized because the fossils it forms are mostly discrete body parts.

Then why can the strange shrimp fossils in Maotianshan Mountain in Chengjiang be preserved so completely?

It turns out that Chengjiang area was not a high mountain in ancient times, but a shallow sea slope. This terrain is a place where mud flows frequently. Whenever there is an accident, the swallowed animals are wrapped in layers of fine mud. The soil attached to animals can greatly weaken the erosion of biological software by water, gas and some microorganisms, thus retaining the body surface characteristics of these sealed creatures.

The fossil group produced by this landform has the ability to preserve the soft tissue structure of animals to the maximum extent, so it is called "specially buried soft-body fossil bank". It is in this fossil bank that the strange shrimp is finally seen by the world. Since then, several newly excavated complete strange shrimp fossils have also been found in Chengjiang fossil biota.

The discovery process of kiwi shrimp is so difficult and tortuous, but the reason why it becomes the overlord of the earth is much more "simple and rude".

The first reason: it is big enough.

How big is this shrimp?

It's about 60 centimeters long, and it's actually as big as a puppy. But don't doubt the description of "big". After all, kiwi shrimp was a CAMBRIAN creature more than 500 million years ago. At that time, other animals were only a few centimeters or even millimeters long. In contrast, kiwi shrimp is not a "big MAC".

Not to mention the huge existence of two meters in the strange shrimp species that appeared in the later period. In this size gap, we want to crush an ant to deal with our prey. It's as simple as that.

Moreover, it also has weapons-its forelimbs, which are mistaken by scientists for the tail of shrimp. Compared with most other creatures with only software but no self-protection ability, Kiki shrimp's two hard and prickly forelimbs are undoubtedly its best weapon. The strength of these forelimbs can easily crush the shell of shellfish, which was the strongest defense that animals could have at that time. Even trilobites wrapped in hard exoskeletons were in Qiqi shrimp's recipe.

It can be said that the top consumption status of kiwi shrimp in CAMBRIAN is beyond my reach.

Another advantage of kiwi shrimp lies in its eyes.

It may be hard for people nowadays to imagine that most ancient creatures actually had no eyes. Even in CAMBRIAN, when creatures with eyes finally appeared, there were very few creatures with eyes. And strange shrimp is one of the few people who care about God.

Shrimp not only has eyes that most animals don't have, but also has compound eyes. Shrimp has as many as 16000 single eyes on each eye. Even now, the number of monocular eyes can be compared with it.

In the face of such a pair of big eyes that can lock the prey 360 degrees without dead ends, no animal can escape. What's more, these animals are basically "really blind" and can't see the road clearly, let alone find a hiding place. Once they are targeted by strange shrimps, they can only give in easily.

However, after the kiwi shrimp evolved to be bigger and bigger, they gave up the practice of predation. The spines on the two forelimbs like shrimp feet are connected together to form a fine "filter screen", which enables it to feed by filtering tiny creatures in the sea. This method of filtering food is very similar to the whale, the largest marine life today. Therefore, kiwi shrimp has become the oldest filter-feeding organism discovered by human beings so far.

It seems that the evolution into a filter-feeding creature is the necessity of the evolution of giant marine life in different periods. Although the Cambrian species explosion can not be explained by Darwin's theory of evolution for the time being, the evolution of these large marine creatures seems to be wonderfully combined with the principle of natural selection here.

Unfortunately, in the long process of evolution, many animals gradually evolved stronger bodies and hard shells, perhaps because of the "arrogance" of strange shrimp. However, there is no other evolutionary direction except that it is larger and has a "filter screen".

After all, the world is a jungle. After the survival became unsustainable, the exotic shrimp also fell from the top throne of the food chain and finally disappeared in the long river of time.

The earth has also restarted a brand-new era.

* References:

The keen vision and the origin of compound eyes of the giant CAMBRIAN predator Anomalocaris.

Patterson Johnson; ; Garcí a-Belidor Diego C; ; Lee Michael S Y；; ; Brocklegren a; Jago James b; Edgecombe Gregory D, Nature, 2011-12-08, PubMed Journal.

The largest CAMBRIAN animal, Anomalocaris, Burgesshale, H.B. Whittington, British Columbia; Journal of Briggs Philosophy of the Royal Society of London. Series B, Biological Sciences (1934- 1990), 1985-05- 14, Journal of the Royal Society.

A variety of large carnivorous shrimp fossils were newly discovered in Chengjiang biota. Fossil Net, 205438+07.438+0.38+03.