Basic introduction Chinese name: chrysanthemum stone Latin scientific name: chrysanthemum stone alias: ophiolite kingdom: animal kingdom: mollusca class: Cephalopoda subclass: chrysanthemum stone subclass: 280 genera: 2000 distribution area: marine basic introduction. Shao, ammonite-evolution and development, ammonite details, morphological characteristics, ammonite shell structure, ammonite suture changes, systematic classification, distribution, evolution and development, collection value, research significance, and others. Amon's incarnation is related to snake stone, and ancient chrysanthemum stone is related to octopus and squid. The cephalopod mollusks of the subfamily Ammoniaceae were introduced. It was abundant in the late Paleozoic and Mesozoic. Extinct about 100 million years ago. Its fossil shell is coiled straight, with a diameter of 200 cm. The inner shell is divided into many small spaces to provide buoyancy. It lived from Devonian to the late Cretaceous, so it was named because it usually had chrysanthemum-like lines on its surface. The knowledge about ammonite animals mainly comes from ammonite shells and covers preserved as fossils, which are obtained by observing the distribution and preservation of ammonite in strata and comparing it with nautilus living in modern oceans. Ammonites evolved from Nautilus in the early Devonian 400 million years ago. In the following 370 million years, ammonites existed in a large number of oceans all over the world until the Cretaceous, when they were extinct from the earth together with archery stones, terrestrial dinosaurs and other marine species. Chrysanthemum stone-evolutionary chrysanthemum stone first appeared in the early Paleozoic Devonian about 400 million years ago, flourished in the Mesozoic, and was widely distributed in the Triassic oceans all over the world. So it was 65.438+0.7 billion years earlier than the appearance of dinosaurs. Ammonites evolved from nautilus and belong to cephalopods. The motor organ is in the head. There is a hard shell outside the body-this is its own residence, similar to the shape of a nautilus. In the evolution of cephalopods, except nautilus, other species no longer carry heavy hard shells, but go into battle lightly. There are many shapes of ammonite shells, such as triangle, cone and rotation, among which the rotation shell is the most. The shell of chrysanthemum stone is also divided into front, back, back and abdomen; . The size of ammonite shells varies greatly, the average shell is only a few centimeters or dozens of centimeters, and the smallest shell is only 1 cm. The big one is 2 meters.
"Simplicity" is the earliest kind of chrysanthemum stone. A large-scale extinction occurred 245 million years ago, which made "chamomile stone" disappear from the earth. Later, the "tooth chrysanthemum stone" appeared. When this animal became the main marine animal in Triassic, dinosaurs also began to live on land. But "ammonite" disappeared at the end of Triassic about 200 million years ago. Later, there were "abdomen chrysanthemum stone", "goat stone" and "arrow stone". The detailed information of ammonites is characterized by cephalopods, and the moving organs are in the head. There is a hard shell outside, similar to the shape of a nautilus. The size of ammonite shells varies greatly, with the average shell being only a few centimeters or dozens of centimeters, and the smallest one being only one centimeter; The biggest one is bigger than the big millstone in the countryside, which can reach 2 meters. There are various shapes of ammonite shells, such as triangle, cone and rotation. Generally speaking, there are outer cylindrical shells, inner cylindrical shells, rod-shaped shells, tower-shaped shells, outer triangular shells and irregular spiral shells. Round shells with rings inside and outside account for the vast majority of ammonites. The shell of chrysanthemum stone is also divided into front, back, back and abdomen. This is the same as the modern nautilus, with the front opening and the back shell. The outer part of the rotating ring is the abdomen, and the corresponding surface of the abdomen is the back. The shell structure of chrysanthemum stone is a conical tube with calcium carbonate as the main component. The initial end of the shell tube is small, usually spherical or barrel-shaped, which is called fetal shell. Most ammonite shells revolve around the fetal shell in a plane, and a few shells are straight, spiral or other irregular shapes. Each shell ring of a planar spiral shell is called a spiral ring, its periphery is an abdomen, the side around the internal spiral ring is a back, and the shell surface between the abdomen and the back is a side. In the process of growth, ammonites periodically move forward in ascending order, and behind them, a partition wall is secreted by the mantle to support the animal's body, increase buoyancy and strengthen the shell. Therefore, shells can be divided into two parts: the part where animals live without partition walls is called the living room; The part with a series of partitions is an air shell, and the space separated by two adjacent partitions is called an air unit. The partition wall is a curved surface, which usually has a complex shape, especially near the shell wall. The contact line between the partition wall and the shell wall is called suture line, which is a very important symbol in the classification of ammonites. Each partition has a circular partition hole, which is where the barrel is located. The body tube can connect the soft body and the shell, and adjust the buoyancy to lift the shell. It is usually located at the edge of the abdomen, but a few types of body tubes are located at the back or near the center. The spinning degree of ammonite shell is very different, which can be roughly divided into loose winding, contact winding, external winding, semi-external winding, semi-internal winding and internal winding. Shells are also varied in shape: from thin plates to spheres, some are triangular spirals, some are straight rods or rings, and the abdomen is pointed, flat or round. Sometimes the surface of the shell is smooth, and sometimes there are different types of decorations. Common decorative patterns include growth line, longitudinal stripes, transverse ribs, tumors, thorns, grooves and ridges. These decorations have many changes because of their thickness, strength, density, direction and mutual combination. In addition, there are different types of ribbons on the surface of shells, but most of them cannot be preserved on fossils. The shell of the ammonite is covered with a film. Some are single valve (single valve), some are double valve (double valve), and some are formed by fusion of double valves (closed valve). Usually, the lid is kept separately from the ammonite shell. Petal ammonite fossils are very rare. Systematic classification marks of ammonites include shell shape, coiling degree, shell surface decoration, body tube position and suture characteristics. The variation of ammonite suture, in which the characteristics of suture are of great significance. Each suture can be divided into outer suture and inner suture. The outer suture is a section of suture on the outer surface of the shell, and the inner suture is a section of suture on the back. The basic elements of stitching are leaves and saddles. The leaf is the part where the suture bends backward, while the saddle is the part that bends forward. According to the distribution position of leaves and saddles, they are called abdominal leaves (or abdominal saddles), dorsal leaves (or back saddles), lateral leaves (or side saddles) and so on. A series of folds in which the suture line does not completely become an independent saddle and side leaves are called ridge line system; A series of secondary saddles and leaves located between the ventral leaves and the first lateral leaves are called even saddles and leaves. There are two ways to proliferate leaves and saddles: ① Saddle-splitting type, which splits from saddle to form independent leaves and saddles; The chrysanthemum stone (2) is lobed, partially splitting from the leaves to produce new leaves and saddles. According to the shape of leaves and saddles, ammonite suture can be divided into four basic types: ① non-edge ammonite type: leaves and saddles are complete, with a small number, only round leaves with a width of 1 on the side, which are found in Devonian ammonite; (2) Prismatic ammonite type: leaves and saddles are complete, and there are many sharp leaves, which are found in ammonites from Devonian to Triassic; ③ Dentate ammonite type: complete saddle-shaped and serrated leaves, found in carboniferous to Triassic ammonites; ④ ammonite type: leaves and saddles are strongly forked or dentate, which is found in ammonites from Permian to Cretaceous. The characteristics of suture are the main signs of dividing orders and suborders, and also the important signs of dividing families, families, genera and even species. The position and direction (forward or backward) of fetal shell and body tube are also important in dividing orders and suborders. Shell decoration plays an important role in determining genera and species and some families. The shape of the shell and the degree of coiling are the signs of dividing genera and species. Generally speaking, the shell difference between ammonite and nautilus is that the shell of ammonite is slightly thin, the body tube is relatively simple, and the partition wall extends to the shell mouth. In addition, the most important thing is that ammonite has complicated suture, while Nautilus has no suture. Suture is the line where ammonite partition wall contacts the inner surface of shell wall. The sutures of other cephalopods are simple arcs or straight lines, while the sutures of ammonites are quite complicated, so any description and classification of ammonites must be based on the discussion of their sutures. The part of the suture that bends towards the shell mouth becomes a saddle, and the part that bends in the opposite direction becomes a leaf. According to the different positions in the shell circle, it is named as abdominal saddle, abdominal leaf, back saddle and back leaf. According to this, there are several types of suture: a. It is composed of some simple saddles and leaves, which is called ammonite suture, and most Paleozoic ammonite animals have this kind of suture. The ammonite suture line B consists of serrated or fringed blades and a round uninterrupted saddle, which is called the ammonite suture line. The ammonite is a typical example of this kind of suture, which was dominant in Mesozoic Triassic. C. Sutures in which leaves and saddles are trimmed and differentiated into many lobules are called ammonite sutures, which mostly appear in Jurassic and Cretaceous. There are several different schemes for systematic classification of ammonites. One of them is to divide ammonites into 9 orders: Archaean ammonites: neck-shaped tube at the back of abdomen. During the individual development, all lateral leaves or lateral leaves move sideways to form more umbilical leaves, Devonian. It can be divided into four suborders: Basopoda: the shell is straight or arched, the spherical fetal shell has ventral leaves, and the fashion has all lateral leaves; Chitin ammonite: early middle Devonian, annular shell or spiral shell, with umbilicus and all-sided leaves; Archaean-like ammonites: from the late Devonian to the late Devonian, during the individual development, the umbilical leaves remained on the umbilical line or moved laterally; Arthropoda: During the ontogeny, lateral leaves and ventral leaves split to produce a series of ribbed leaves and occasional leaves, in the early Late Devonian. Prismatic ammonite: abdominal tube, ovoid fetal shell, with 1 to several lateral lobes in the process of individual development, which was formed by lateral saddle cracking, Middle Devonian-Permian. It is divided into two suborders: round-leaved ammonites: simple ventral leaves without bifurcation, Middle Devonian-Permian; Prismatic ammonite: The basic suture is 8 leaves: a three-part ventral leaf, a pair of first lateral leaves formed by the division of lateral saddle, a pair of lateral leaves close to navel, a pair of middle leaves and a dorsal leaf. Each leaf can be divided into two or three parts by one or more leaves to form more leaves, Early Carboniferous-Permian. Poseidon: Dorsal canal, ovoid fetal shell, late Late Devonian. It is divided into two suborders: the genus Rabdosia: the original genus contains a ventral leaf, some genera have lost ventral leaves, and there are more leaves and saddles, in the late Late Devonian; Poseidon suborder: without ventral leaves, simple suture, late Late Devonian. Anterior disk ammonites: ventral posterior trunk tube, ventral leaves narrow and trigeminal, dorsal leaves narrow, simple or dichotomous, with developed rib system, Early Carboniferous-Late Triassic. Tooth ammonites: the body tube moves from the near central position to the ventral side during the individual development, and the suture lines are mostly tooth ammonites, and a few are marginal ammonites or ammonites, Permian-Triassic. Phyllostachys pubescens: ammonite suture, saddle-shaped differentiation into many small round leaves, Triassic-Cretaceous. Chiammonites: flat shell, ammonite suture, few leaves and saddles, multiple bifurcation, ribbed thread system, dorsal blade tip, Jurassic-Cretaceous. Ammoniaceae: ammoniacal suture, simple or complex, saddle-shaped mainly divided into two parts, sometimes divided into three parts, but without leaves, and then divided into two parts, Jurassic-Cretaceous. Turmeric: The shell is flat and coiled, or irregularly curled, or even straight. The ammonite suture has only one dorsal lobe and ventral lobe, a pair of lateral lobes and umbilical lobes, the ventral lobe is bifurcated, the lateral lobe is bifurcated or trigeminal, Jurassic-Cretaceous. Under orders and suborders, it is further divided into superfamily (about 80), family (about 280) and genus (about 2000), as well as many species and subspecies. It has been distributed for a long time, and many scholars speculate that the ammonite with snail shell is a rod-shaped stone with straight shell, which gradually bends and evolves into an edgeless ammonite with ring shell. However, stratigraphic evidence shows that the oldest ammonites with annular shells and arcuate rods appeared almost at the same time. Therefore, some people think that rod stone and non-edge ammonite evolved from right-angled stone with oval shell and ventral tube almost at the same time. All ammonite fossils are produced in shallow sea sedimentary strata and coexist with many marine fossils. Through the determination of paleomagnetism and paleotemperature, the analysis of lithology and lithofacies, and the study of paleoecology of ammonites, it is concluded that ammonites live in tropical to temperate waters with a certain depth, and their living habits are different because of the different shell wall thickness, shell shape and shell surface decoration. For example, the type of thick shell wall decoration is relatively inactive; The type with thin shell wall, smooth surface and pointed cake shape is active and inhabits deep water. Chrysanthemum is the most effective standard fossil for stratigraphic division and correlation because of its rapid evolution, wide distribution and easy identification. According to the vertical evolution of ammonite in strata, quite fine ammonite zones are divided. For example, in the Triassic, Jurassic and Cretaceous of Mesozoic, more than 30 ammonite belts can be divided in each era, and the average duration of each ammonite belt is between1~ 2 million years. There are 30 ammonite belts in the late Paleozoic strata of Western Europe, and the average duration of each ammonite belt is less than 500,000 years. Using isotopes and other methods to determine the absolute age of strata is far from this accuracy. There are many kinds of ammonites in Paleozoic and Mesozoic strata in China, especially Devonian ammonites in Guangxi, Permian ammonites in South China, Triassic ammonites in Guangxi, Qinghai and Tibet, and Jurassic and Cretaceous ammonites in Tibet, which are of great significance. There are records of ammonite fossils in the marine strata of Guangxi, Guizhou, Qinghai and Tibet, especially in the Everest region of Tibet, where a large number of ammonite fossils are produced and even readily available. Because in Mesozoic, this is the ancient Himalayan Sea. With the tectonic movement, the crust rises, the seabed becomes mountains, and ammonite fossils are exposed. People used to call this kind of animal with ribs, ribs and ridges on its shell "Amon Angle" or "snake stone". Evolution and development In the evolution of cephalopods, only nautilus is still carrying a heavy hard shell and swimming slowly in the water, relying on the hard shell to protect itself, while other species have removed the hard shell and advanced lightly in evolution. According to the movement mode of Nautilus, Nautilus is also an animal with poor swimming speed and poor movement consistency. There are many shell ornaments on the surface of ammonite shells. Shell decoration is the general name of growth line and growth line parallel to screw. Some are vertical lines parallel to the winding direction of the shell, and some are horizontal lines perpendicular to the direction of the shell. The ammonite shell is mainly composed of calcium carbonate, mostly flat-rotating shell. The shell rotates around the tire shell in one plane, and a few shells are straight shells, spiral shells or other irregular shapes. During the growth of ammonites, partition walls are periodically secreted from the mantle, and the space between two adjacent partition walls is called air chamber. The contact line between the partition wall and the shell wall is called suture; Each partition has a circular partition hole, which is where the body tube is located, usually at the edge of the abdomen, with a few at the back or near the center. Sometimes the surface of the shell is smooth, sometimes it is decorated with growth lines, longitudinal lines, transverse edges, tumors, thorns, grooves and ridges, and the shell mouth of the chrysanthemum stone is covered. The characteristics of suture are of great significance in the systematic classification of ammonites. Each suture can be divided into an outer suture on the outer surface of the shell and an inner suture on the back surface. The basic elements of stitching are leaves and saddles. The leaf is the part where the suture bends backward, while the saddle is the part that bends forward. According to the distribution position of leaves and saddles, they are called abdominal leaves (or abdominal saddles), dorsal leaves (or back saddles), lateral leaves (or side saddles) and so on. A series of folds that do not completely become independent saddles and side leaves are called ridge lines. According to the shape of leaves and saddles, ammonite suture can be divided into non-prismatic ammonite, prismatic ammonite, dentate ammonite and ammonite. The outlet of the soft part is also the opening of the shell. The shape of the shell mouth is also different, such as round and oval, and the abdomen is generally curved. There is a lid at the mouth of the shell, which is called a lid. Its composition is calcium or keratin. When the soft part retracts into the shell, the flip cover tightly covers the mouth to protect the soft part. The cover only appeared in the early Devonian, which can be divided into two types: one is the single-mouth cover that appeared in Triassic, and the cover is horny and cannot be completely closed; The other is the double-mouth cover, which only appeared in Jurassic and Cretaceous in Mesozoic, and consists of a pair of calcareous thin sheets that are roughly triangular and slightly protruding outward. The valuable ammonite fossils are all produced in shallow sea sedimentary strata and were born together with many marine fossils. It is speculated that ammonites live in waters with a certain depth from tropical to temperate zone. The ammonite is the most effective standard fossil for stratigraphic division and correlation, which can be divided into quite fine ammonite zones. All kinds of ammonites contained in Paleozoic and Mesozoic strata in China are of great significance. Devonian ammonites in China are mainly produced in Nandan, Guangxi, and Carboniferous fossils are also mainly produced in Guangxi. Permian ammonites are widely distributed in southern China. Triassic ammonites are mainly found in Guizhou, Tibet, Sichuan and Hubei. There are a large number of Jurassic ammonite fossils in the Everest region of Tibet, even ready-made, because it used to be the ancient Himalayan Sea more than 200 million years ago. Due to orogeny, the crust rises and the seabed becomes a mountain. Therefore, ammonites living at the bottom of the ocean appear on the ground, which has become a witness to the crustal movement and change in the Himalayan region, and also provides favorable evidence for restoring the local paleoecological environment. There were few ammonites in China in Cretaceous. The longitudinal section of ammonite fossils is beautiful spiral, brown and translucent, and the color is like amber. People in Fujian and Taiwan believe that chrysanthemum stone can be transported and circulated, which brings good luck, good feng shui and likes to collect. It is placed indoors in pairs. The individual is huge, the color is gorgeous, the price is high, and the exquisite collection can be called gem-level collection. 20 12 Taiwan Province province sold 70cm diameter pieces of chrysanthemum stone, a pair of which was worth NT$ 800,000. However, the overall output of chrysanthemum stone is very large, and the scientific research value is greater than the collection value. Research Significance The ammonite is the most useful fossil for dating rocks. Using ammonites, experts can accurately divide the geological age to 500 thousand years. Compared with the age of the earth of 4.6 billion years, 500,000 years is a very short time. Most of the Jurassic and Cretaceous periods were divided by ammonites. Chrysanthemum fossils are widely distributed-similar fossils may be found thousands of miles apart. This is because in Jurassic, Pangu continent began to split, which provided a waterway for ammonites to spread all over the world. The scientific names of Amon and other incarnations of serpentine chrysanthemum stone come from Amon in ancient Egypt. The priests used the head of a sheep to represent the image of Amon. The bent horn of a sheep is similar to an ammonite shell, which is a symbol of the goat god. In 88 AD, Pliny, a famous Roman naturalist, first mentioned the ammonite in his works. He called the Ammonites the Horn of Amon. Amon was originally the Egyptian god of wind and air. From 2000 BC to 1360 BC, Amon occupied a prominent position among the Egyptian gods and was regarded as the first god of creation. Thebes who believed in Amon built the temples of Karnak and Luxor to worship Amon. One of the representative symbols of Amon is a ram with two spiral angles, which is very similar to the shell of an ammonite. Therefore, Pliny regards the ammonite as a sacred stone, and thinks that it has magical power and can evoke the future.
In the Middle Ages, people regarded the ammonite as a headless snake with coils, which made it full of mystery. In Britain, chrysanthemum stone is called "snake stone". In a small town in Yorkshire, England, it has always been said that the chrysanthemum stone is a headless snake, and its head was cut off by St Hilda in the 7th century. So the city emblem of this small town is painted with three snake-headed ammonites. It is said that wizards can use ammonites to make sleeping gods appear. The incarnation of Amon, an ancient ammonite creature, is related to octopus and squid. 400 million years ago, nautiluslike, an ancient ammonite creature, roamed the vast ocean looking for fish and other prey. Nautilus has dozens of tentacles and lives in spiral or conical shells, which paleontologists have always thought. However, a new study recently found that many members of this ancient family are motionless creatures, and they spend most of their time in places where methane bubbles appear on the seabed. These creatures are related to octopus, squid and cuttlefish.