Take you to grasp the "ghost" in the fossil

Although there is no "ghost" in reality, there are some biological groups called "ghosts" in the field of paleontology.

These "ghosts" are not lonely, they are called "ghost branches". Do you want to see this little partner, "Good guy, you will also make the biological evolutionary tree of 'ghost'? This is unscientific!"

Ghost evolved tree (picture source: authors self -made)

No, non -, but they do come from related analysis of biological evolution. To tell this story, it must be told in 1970.

Before this time, paleontologists believed that the age of fossils was consistent with the age of the rocks around it. If it is based on the logic of this view, it is not difficult to find that the order of these creatures that become fossils appear on the earth stage can be determined by the age of their rocks. In other words, the earlier the rocks where biof fossils are located, the earlier the time for this creature to appear on the earth stage.

Does it sound very reasonable? If you feel that it seems logical, you need to understand the relationship between biology, fossils and rocks first.

1. Jump from alive to being photographed into a slate

If the remains of the creature or the relics left during life in ancient times, if they want to become a fossil, they need to be buried first, and then the pressure on the body or relics will gradually increase as the coverage of the cover is gradually increased. Compact, becoming a rock.

This process is simple, but in fact, each fossil must go through a test when forming. The first problem comes from its body. Biological itself usually has both the hardware and the software. When rotten after death, the software will almost be destroyed, and only the hardware can be preserved.

Most of the fossils we see are hardware such as bones of creatures, and their software has long died over time. Image source: wikipedia

The following is the physical and chemical conditions that were exposed after death. If the energy of the water or wind sand is too strong, the body or relic will be worn and destroyed, and there will be no chance to be buried at all; in addition, if the acid and alkali and oxidation and restore environment of the environment will also affect the preservation of the organic body.

Then the burial link, the ingredients of the cover can also affect the integrity of fossils. For example, under different environments such as sediment, glaciers frozen soil, and half -cooling magma, the fossil integrity saved will be much different.

After that, the part of the rock is formed, which is also the time to form a fossil. At this stage, the physical squeezing of the outside world and the exchange of chemicals such as groundwater solution will also have different degrees of destruction of fossils.

Even after the fossil formation (that is, after becoming part of the rock), they will be destroyed in the long underground time due to continuing to be squeezed, underground calories, or other factors. On the day of being discovered by humans.

Two dinosaurs from death, buried, and rock to excavation. Image source wikipedia (https://zh.wikipedia.org/wiki/%E5%9F%8B%E8%97%8F%E5%AD%A6 #/media/fossilization_Process.jpg))

Each step in these processes is a large screening. The fossil we can find now is only a few paleomantic remains and relics that are fortunate to be preserved. Outside of them, the traces of countless creatures have long been gone by time.

It is precisely because the remains and relics of most creatures cannot be preserved, so whether it is the type of paleontology or the time of the survival of paleontology, its fossil records are very incomplete.

Picture source: Weibo

About 1970, paleontologists have gradually noticed this problem and began to seek logical more rigorous ways. Since the rock can't stand, let's take a look at the fossil itself. Paleontologists have extracted the information reserved on the fossils and summarized the "features" that can describe fossils, and these characteristics are the key to helping the survival time of paleomantic creatures.

These features are in accordance with whether the order of organisms can be reflected in the order of organisms can be divided into "ancestors" that reflect the characteristics of their ancestors and "derivatives" that reflect the characteristics of future generations. The ancestors and derivatives can be said to be a complementary definition.

The characteristics of the biological rooms are the ancestral signs. For example, all vertebrates have spine; and the corresponding derivatives refer to the characteristics of only a part of the creature and other creatures, just like birds and some dinosaurs have feathers with feathers grow feathers. But there are many other dinosaurs without feathers. Through this method, you can roughly determine the sequence of different groups of creatures in the history of the earth, and then it can infer the time point of a certain group that evolved its own characteristics. This time node is the time when this group of biological theory has evolved.

A and B are two biological groups with common ancestors; T1 is a time node separated from the evolution of these two biological groups; T2 is the time node when the B group discovered; T2 is always equal to or later than T1. Discovery time and evolution of fossil species

However, reality is always unsatisfactory, not to mention the "real" that has to surpass millions of years. The preservation of fossils is incomplete, and the missing information will cause the evolutionary time node to be earlier than the earliest fossil records. Because there is no fossil evidence, during this period, such creatures have become a state of existence of theory but in fact. As a result, "ghost" was born. In this period of no fossil evidence, the evolutionary tree that should theoretically exist is its "Ghost Lineage". In addition, there is a word "Ghost Taxa" at the same time as the ghost branch, which is translated as "ghost group". As the name suggests it is a "ghost" itself, but it is different from the ghost branch. Although it has not been found, it can be theoretically inferred that it has offspring. From the perspective of evolution, its extinction has evolved into its descendants. For example, a category of beast -like dinosaurs evolved into birds. This type of dinosaurs are now extinct, but the descendants of its evolution still exist. If this type of dinosaurs have not been found so far, then such dinosaurs are ghost groups. In other words, the ghost group is a group that exists only in the evolutionary analysis and is a product of pure theoretical analysis. For example, E in the figure can be called a ghost group.

A, B, C, and D are four species. Figure i shows the evolutionary relationship between these four species; the E and F in Figure ii are the ancestors of A, B, and C, and D, respectively; -10 represents the order of time, 10 is the oldest, 1 latest, the solid line is the time for fossil records, and the dotted line is the existence time inferred by system evolution. The part of A, D is called the ghost branch, while E is called the ghost group; what about F? Because the appearance of C is already 10, the appearance of F for the ancestor must be earlier than 10, then it is naturally not seen in this picture. Ghost branch, ghost group interpretation diagram (modified from norell, 1993)

The clever friends are afraid to be able to give up at this time. Will there be a simple theory that can be concluded and did not find the ghost branch of the actual stone?

The answer is yes, as long as it lives long enough and its fossils have not been found! For example, Latimeria, which can be seen in the ocean now.

Second, the living ghost

One of the most famous "Ghost Branches" in the current fish is Latimai fish, also known as spear feet. It is located in the genus of Ratimai Fishtimai fish in cavity. Or brown tone, deep -water fish with meat fins and white spots.

Lattima fish pictures found near the South African coast Source: BRUCE Henderson

In addition to being followed by biology and paleontologists, it also loves the favorite role of Japanese game companies that add fishing elements.

Lattima fish in "FF14", screenshot of the game

Lattima fish in "Monster Hunter World: Icefield", screenshot of the game

The ancient vast fish in Pokémon was quoted from wiki.52poke.com

In 1938, people discovered the living West Indian Ocean Latimeria Chalumnae in South Africa. This is the most classic source of Lattima fish image and the dark blue background. In 1997, another brown -gray Indonesian Latimeria Menadoensis was discovered in Indonesia.

Indonesia's Latimai Fish Picture Source: wikipedia

At present, Latimai fish is only composed of these two species. From the perspective of the evolutionary tree obtained by analysis, Latimai fish is separated from its sisters in the early days of charcoal. The analysis results of the molecular clock show that the two species of Latimai Fish started to form their own differences from a common ancestor from a common ancestor. Evolution path. However, to this day, the paleontologists have not found any fossils of Lattima fish except the two existing Lattima fish. The vacancies of this fossil record made Latima fish a "ghost branch" from the early days of charcoal.

The Red Line is a picture of the ghost branch Latimai fish ghost branch (author painted)

Third, the ghost in fossils

In 2008, the early vertebral animal research team of the Institute of Ancient Sciences of the Chinese Academy of Sciences discovered a hard -saving hard bone fish in the late stratum of Qu Jingzhi, and published it in the British "Nature" magazine. This fish is a fantasy ghost fish. Although it is a hard bone fish, it brings together the characteristics of hard bone fish, cartilage fish, shields and spiny fish, to shorten the relationship between hard bone fish and "relatively ancient" shield fish.

Specifically, its head armor can be divided into top nails and rear tops in morphology, which is the same as early meat finfish; its cheek bones are similar to the early spokefish The decoration is also closer to the spokefee fish; its shoulder strap has a spine spines before the pectoral fin, which is similar to the early meat fin fish (such as spots), early cartilage fish, spine fish and shield fish; The large block of the midline may be equivalent to the same position in the same position in the shield -leather fish. Before it saw it again, the researchers had found that the spots in the early meat fin fish were with the same spine thorns as shields, spiny fish and cartilage fish, but because the spots of scales were found at the time The materials are scattered bone slices, so the characteristics of group groups in the early days that are associated with mandibular fish, spiny fish, cartilage fish, and hard bone fish have made researchers always doubt. After the discovery of ghost fish, its system development analysis shows that it is located in the base of meat fin fish. This confirms the wonderful feature of spots and shields, spiny fish and cartilage fish with the same spine, fill the empty position of early vertebrate evolution. Since it is filled with empty positions, it is a ghost before it was discovered. The evolution of the ghost fish is located. Picture source: reference [8]

After discovering such a ghost, paleontologists would not let it go easily. The naming of paleontology follows the two methods of biological names, consisting of the name of the name and the front and the second part of the species. The name of the fantasy ghost fish is the Latin "Oneiros", which is derived from the son of the Greek mythical night goddess of the Greek mythical night goddess, the Dream God Aielos, which has the meaning of highlighting the fish in the dream. And its name is "Guiyu", which is simple and straightforward Chinese pinyin. One is to take the meaning of "ghost talents", which refers to the characteristic monster; the other side is the name of the "ghost branch" of the ghost branch, Not only are the features, but it is also a ghost that has been evolved with paleontologists in the tree before, and has always wanted to find a ghost 400 million years ago.

Fantasy ghost fish recovery picture source: reference [6]

Produced: Popular Science China

Author: Cai Jiachen

Producer: China Science Popularization Expo

references

[1] Norell M A. Tree-Based Approaches to UndersTnding History; Comments on Ranks, Rules and the Quality of the Fossil Record [J]. American Journal of Science, 1993, 293 (A): 407. 407. 407.

[2] Encyclopedia Latimer

[3] Inoue J G, Miya M, Venkatesh B, et al. The mitochondrial genome of Indonesian coelacanth Latimeria menadoensis (Sarcopterygii: Coelacanthiformes) and divergence time estimation between the two coelacanths[J]. Gene, 2005, 349: 227-235.

[4] SUGEHA H Y, POUYAUD L, HOCDé R, et al. A Thirteen-Million-Year Divergeeen Two Lineages of Indonesian Colacanths [J]. Scientific REPORTS, 2020, 10 (1): 1-9.

[5] zhu m, zhao w, jia l, et al. Et al. ELDEST Articulated Osteichyan Reveals Mosaic Gnathostome Character [J]. Nature, 2009, 458 (7237): 469-474.

[6] Yu X B, Zhu M, Zhao W J. The Origin and Diversification of Osteichthyans and Sarcopterygians: Rare Chinese Fossil Findings Advance Research on Key Issues of Evolution[J]. Paleoichthyology, 2010, 24(2): 71-75.

[7] John, Zhu Min. Zhili-li-lirate's fins of meat and fish.

[8] Lu Jing, Zhu You'an, Zhu Min. Our ancestors came from the water-the origin and early evolution of hard bone fish [J]. Natural magazine, 2016, 38 (6): 391-398. [9] Zhao Wenjin. Fantasy Fantasy.Ghost Fish: The oldest hard bone fish [J]. Collection, 2009, 6.

The China Science Popularization Expo is the Science Popular Science Platform of the Chinese Academy of Sciences. It is sponsored by the Computer Network Information Center of the Chinese Academy of Sciences. Relying on the high -end scientific resources of the Chinese Academy of Sciences, it is committed to spreading cutting -edge scientific knowledge and providing fun science and education services.

- END -