Figure 4-25 Types of bivalve activity patterns
(According to Stanley 1972, slightly modified)
1~ 3-epiphyte; 4- wandering; 5 ~13-hidden point; 14 ~ 15- drilling
Figure 4-26 Relationship between the Depth of Hidden Cave and Water Depth
(quoted from Babin, 1980)
Bottom left: shows the development types of water pipes in deep dive holes in coastal areas; Lower right: Subsea species with deep-water and shallow-water dive holes.
There are different opinions on the classification of Cephalopods. Cephalopods are divided into four subcategories in this book. See Table 4-7 for comparison with other subcategories.
Table 4-7 Cephalopod Classification Table
Figure 4-27 Living Cephalopods
(According to Taichet, 1964)
A-b- Nautilus (Tetrabranchia), A- longitudinal section; B- maxilla and mandible; C-d-septia sp (Dipranchia), C- longitudinal section; Maxillary and mandible
Nautilus (Nautiloidea)
1. form
Nautilus shells are mostly straight cones, but there are other types (Figure 4-28). Shells vary in size, from a few millimeters to more than 9 meters long. The shell is divided into a body cavity and a closed cone (Figure 4-29). The body room, also called the living room, is located at the front end of the shell, where the software lives. The opening is outward, and the ventral surface is often concave, which is called funnel bend (ventral bend), and the funnel protrudes from here. The closed cone is the remaining part of the shell outside the body chamber, which is divided into many air chambers by the partition wall, and the initial end is the original shell. The partition wall is a side partition wall secreted by the rear edge of the mantle, which is used to support the software. With the continuous growth of living things, the software moves forward, and a new partition wall will be secreted before a certain distance. The software has been living in the body room at the front end of the shell, and there is a tubular cable connected to the original shell at the back end. Each bulkhead has a circular bulkhead hole for the body cable to pass through, and the bulkhead extends backward around the hole into a tubular bulkhead neck, which is straight and curved, with different lengths and many kinds (Figure 4-3 1). An annular neck ring is connected between or inside the bulkhead neck, and the bulkhead neck and the neck ring form a circular tube, and the tube cable is located in the tube. This kind of long pipe that runs through each air chamber and connects the original shell with the living room is collectively called the body pipe. Body tubes are located at the center or edge of the shell and have different thicknesses and shapes. Some tubes can also have various calcareous structures, which are called inner body tubes (also called inner body tube deposition, Figure 4-30). The characteristics of body tube are very important in classification. The line between the partition wall and the inner surface of the shell wall is called suture, which is generally straight, and some suture lines in late Paleozoic and Mesozoic can also be bent. Many Paleozoic nautilus still have air chamber sediments. Most of the shell surfaces are smooth, with growth lines, and some have ridges, protrusions and thorns.
Figure 4-28 Species of Nautilus Shells
(According to Leinisto, 1979)
Figure 4-29 Structure of Nautilus Right-angle Stone Shell
(According to Schlock & Twenhoff, 1953)
classify
The characteristics of shells are the basis for the classification of Nautilus, especially the shape of the body tube is the most important. It can be divided into four superorders (or upgraded to subclasses). See Table 4-8 for the characteristics of each hypereye.
3. Lifestyle and morphological function analysis
Nautilus is all marine life, and only Nautilus is the only living representative of Tetrabranchia, which is distributed from Luzon Island to Samoa Islands in the southwest Pacific Ocean. Nautilus likes to live in waters with a water depth of 500 ~ 600 m, inhabit the seabed during the day or swim slowly in the water near the seabed, and often float on the sea in groups at night. It is generally believed that most fossil nautilus, like living nautilus, can swim, which requires that the end of the body cavity and the funnel be in a horizontal position. However, the shell shape of Nautilus is diverse, so it is necessary to solve the problem of shell balance through different ways, such as secretory air sac deposition and internal body tube deposition, and cut off the early shell to make the shell short and thick, and roll the shell (Figure 4-33, Figure 4-34).
4. Evolution and distribution
Reliable nautilus fossils began in the late CAMBRIAN. Except some suspicious fossils, Plectronoceras, found in the lower part of Fengshan Formation of Upper Cambrian in China, is the earliest known cephalopod. By the middle of Late Cambrian, a large number of species and genera of Eliesmeroceratids had appeared in Orthoclades, forming a huge cephalopod fauna, which was characterized by a small, slightly flat shell, dense next door, many short necks next door and a small body tube in the abdomen. At the same time, there are also early representative nacre and amphibole, which have many similarities with plectronceras and are very close in distribution, indicating that nacre, mother-of-pearl and nautilus all evolved from plectronceras. By Ordovician, nautilus developed in large numbers and differentiated rapidly. Their shells became larger, some of them were several meters long and varied in shape. Generally, their body tubes were thicker and located in the center or ventral side of the shell, and their structures became more complicated, such as ring bead deposition, star bead deposition and inner cone. Some of them have air chamber deposition. Silurian nautilus is mostly a family and genus inherited from Ordovician, but there are also some special types, with thick and short shells and obvious contraction of the mouth. At the end of Silurian, most of the prosperous species of Ordovician and Silurian were extinct. Devonian is the decline period of Nautilus, Carboniferous and Permian, Nautilus differentiated and developed beyond the eyes, with many shells and many suture lines bent into obvious saddles and leaves. In the late Permian, most of these nautilus became extinct. Nautilus continued to decline throughout Mesozoic. Only a few genera and species remain in Cenozoic, and only one genus, Nautilus, exists (Figure 4-27).
Figure 4-30 Structure types of Nautilus inner tube
(According to Taichet, 1964)
Figure 4-3 1 Nautilus diaphragm neck type
Table 4-8 Main morphological characteristics and representative genera of Nautilus subclass
Figure 4-32 represents nautilus fossils.
(1, 8 quoted from Zhao et al.,1965; 2 according to Zittel,1915; 3. According to 10 ~ 12,1930; 4 ~ 6,9 According to Teichert,1964; 7 According to Grabau, 1922), right-angled stone super net: 1— dinoflagellate of Liaoning Upper Cambrian, with a longitudinal section of ×3; 2— Silurian Michelia× 2 longitudinal section in Europe; 3— Chimonanthus chinensis, 3a. Shape, 3b. Full × 0.5 longitudinal section of Middle Ordovician in Hubei.
Internal hornfeloidea: 4-internal hornfels, longitudinal section, ×0.4, Middle Ordovician, North America; 5— Coleoptera. , ×0.4, Middle Ordovician in Norway; 6— Schematic diagram of the longitudinal section and three transverse sections of Coreanoooceras Kemiponse in North Korea; 7— Daphnia oblata, 7a. Weathered surface of pipe body, 7b. The lateral surface of the lower Ordovician body tube in Hebei is about ×0.4.
Pearl hornoidea: 8-Brachionus, longitudinal section, ×0.8, Lower Ordovician in Liaoning; 9—— Oil termites from the Lower Ordovician coccidia in Inner Mongolia, longitudinal section, ×0.8.
Nautilus suborder:10-Asian acoustic arowana, longitudinal section, ×0.7, Middle Ordovician in Hubei; 11-European Panlong, side view, ×0.5, Middle Ordovician in Hubei; 12 —— Middle Ordovician LII rock in Hubei Province, longitudinal section, about ×0.5.
Figure 4-33 Gas Chamber Deposition and Life Style of Right-angle Stone Shell
(According to Tasch, 1973)
Figure 4-34 Longitudinal section of Nautilus shell in Early Paleozoic
(According to Lyman, 1976)
Showing chamber and body tube deposition
(2) Bacteroides
The shell is small, straight or curved, narrow or wide conical, and the cross section is round or oval. The body tube is thin and simple, located in the abdomen of the shell. The original shell is spherical or egg-shaped, and the living room is longer. The suture line is straight or slightly curved, with wide lateral leaves and narrow and short ventral leaves in a V shape.
Figure 4-35 Geological Age of Nautilus Subclass.
(According to Tychet et al. Moore 1964, simplified)
Figure 4-36 Rod Stone
(quoted from Easton, 1960)
1-bacteria Arkonensis,1a. Abdominal diagram of internal model,1b. The transverse section shows the ventral body canal,1c. A complete shell; 2-Schweitzer's bacterial suture
Shell surfaces are usually smooth, sometimes with horizontal or vertical ornamentation (Figure 4-36). All of them are marine, distributed from Ordovician to Triassic, including only more than 10 genera, with few fossils, and the representative genus is Bactrites.
The rod stone body tube is located at the edge of the shell, and the suture line has ventral leaves, which is similar to ammonite, so it is considered as the original representative of ammonite. However, the stone shell is flat or slightly curved, and the ventral lobe is underdeveloped, which is similar to Nautilus, so it is also classified as Nautilus. At present, it is generally listed as a classification unit at the same level between the two.
(3) ammonites (ammonites)
The shell of ammonite is multi-rolled, and the main difference from Nautilus is that the next door is strongly folded, the suture is very complicated, and the body tube is small and mostly near the abdomen. The ammonites are distributed from Devonian to Cretaceous, and flourished in Late Paleozoic, especially in Mesozoic, with remarkable characteristics and rapid evolution, which can be used to establish fossil belts with a time limit of less than one million years. At the same time, ammonites are widely distributed, and many genera and species are worldwide. It is one of the important standard fossils for detailed division and intercontinental correlation of marine late Paleozoic and Mesozoic strata.
1. form
The shell of ammonite is multi-coiled, symmetrical on both sides, or flat on the side in the shape of a disk or convex mirror, or compressed on the ventral back in the shape of a ball or ellipsoid. Some shells are irregular, spiral, hooked and so on. In a flat shell, one circle of the shell is called the shell ring, and the concave part of the last shell ring is called the navel, and the navel varies in size. The contact line between the outer shell ring and the inner shell ring is called umbilical cord (Figure 4-37). The body tube of chrysanthemum stone is simple, with only one thin tube, and its internal structure is not complicated. Generally, the inner shell has several bulkhead necks extending backward to form a backward-extending barrel, and then gradually changes to the outer shell with a forward-extending bulkhead neck to form a forward-extending barrel (Figure 4-38). The original shell of ammonite is spherical or barrel-shaped, and its width is larger than that of the original atrium. Generally, the shell surface has horizontal shell ornaments parallel to the edge of the shell opening and vertical shell ornaments consistent with the rotation direction of the shell ring, and the rotating rough ridge of the abdomen is called the belly edge. In addition, there may be tumors and thorns.
Figure 4-37 Morphology of ammonite shell
(quoted from Easton, 1960)
Suture The suture of ammonite (Figure 4-39) is complex and important, which is the main basis for classification. The suture is divided into two parts: the inner side and the outer side. The outer side suture refers to the part from the ventral side of the shell through both sides to the contact line (umbilical line) with the previous shell. Internal suture refers to the part between the two umbilical lines on the back of the shell ring, which cannot be directly observed because it is covered by the previous shell ring. Sutures are usually represented by figures, with arrows indicating the midline of the ventral surface, pointing to the shell opening and drawn from the ventral surface to the back. Umbilical cables are indicated by short diagonal lines on the drawings. Because the suture is generally symmetrical on both sides, only one side or only the outer suture is drawn (Figure 4-39, b). The part of the suture that bends towards the shell mouth is called saddle, and the part that bends in the opposite direction is called leaf. Leaves and saddles are named according to different parts of the shell, such as the ventral leaf (outer leaf) in the center of the ventral surface, the dorsal leaf (inner leaf) in the center of the back, and the lateral leaves on both sides. If there is more than one lateral lobe, it is divided into the first lateral lobe and the second lateral lobe from the ventral side to the dorsal side. Saddles located between leaves are also divided into abdominal saddles and side saddles accordingly. Abdominal leaves, lateral leaves and dorsal leaves are called primary leaves, which are found in all ammonites. Leaves differentiated from saddle leaves are called secondary leaves, such as occasional leaves differentiated from lateral saddle leaves and umbilical leaves differentiated from saddle leaves between dorsal leaves and lateral leaves. Umbilical lobe is located near umbilical line, and the small curve outside umbilical line is called auxiliary line. The nature of some adult sutures is difficult to determine. For example, the sutures of Agathiceras and Adrianites in Permian are very similar, but the former occasionally has leaves and the latter does not. This is determined by personal development. Therefore, it is very important to study the individual development of ammonites. There are many types of suture lines of ammonites, which are very complicated, and are important basis for studying the classification and evolution of ammonites. The main types are shown in Table 4-9.
Fig. 4-38 longitudinal section of tropical cf.phoebus
(quoted from Zittel, 19 15)
Shows the change of the extension direction of the diaphragm neck.
Figure 4-39 ammonite suture
(quoted from Lyman, 1976)
Displays the name of each department.
Table 4-9 Main types of ammonite suture lines
The shape of the ammonite shell mouth changes greatly (Figure 4-40). The ventral surface of the Mesozoic ammonite shell often extends forward to form an abdominal sheath, and both sides can also protrude into lateral processes. The mouth of Paleozoic ammonites generally had abdominal curvature. A single horny flake or two symmetrically arranged calcium flakes often appear near the shell or in the body cavity. Previously, it was always thought that it was the lid of a shell (single-mouth lid and double-mouth lid), but recently it was thought that it might be the mandible (beak stone) of an ammonite. Most of the maxilla has not been preserved as a fossil.
Figure 4-40 Morphology of ammonite shell mouth
(quoted from Lyman, 1976)
The adult ammonite shells of the same species found in the same place and in the same horizon should generally be very similar in size, but two kinds of shells with completely different sizes, namely big shells and small shells, are often found. The big shell is several times larger than the small shell, and there is no middle type in the middle. It is generally believed that this is a hermaphrodite phenomenon. Small shells represent males and big shells represent females, which is called hermaphroditism. In addition to different sizes, ammonite shells of different sexes often have different shell mouth characteristics. For example, small shells can have special structures such as lateral protrusions, while the shell opening of large shells is relatively simple (Figure 4-4 1).
Fig. 4-4 1 ammonite diploid
(Quoted from Clarkson, 1979)
1-sea lions (Arisphinctes)ingens；; 2—— rotifer, ×0. 12, both of which may be hermaphroditic.
Figure 4-42 Individual Development and Systematic Development of Breast
(quoted from Miller et al., 1957)
A'-c'-c', d personal development; A-c, d system development
Individual development and phylogeny Because the young shell of ammonite is surrounded by the shell, all the characteristics of the early shell are preserved, which is particularly beneficial to the study of the individual development of ammonite. Individual development reproduces the developmental stage of its ancestor system to a certain extent, and the study of ammonite suture provides an excellent example in this respect. J.P.Smith proposed in 1927 that Permian migmatite evolved from Carboniferous protolith, and Uddenoceras and Uddenites were intermediate types in Late Carboniferous, but after studying their suture lines, it was found that there was still a lack of an intermediate type between them and protolith. This genus was discovered by another scholar in the Late Carboniferous strata the following year (1930) and named as Prouddenites (Figure 4-42).
Fig. 4-43 representative genera of ammonites.
1— Lower Devonian Anetoceras hunsrueckianum, Germany, side view, × 0.46; 2—manticocera impression, 2a. Side view, 2b. Oral view, ×0.44, Upper Devonian, former Soviet Union; 3— Spherical amphibole, 3a. Side view, 3b. Mouth view, ×0.5, Carboniferous; 4—Clymenia laevigata, longitudinal section, 0.37, Upper Devonian, Germany; 5— Upper Devonian Gonioclymenia subcarinata, Germany, side view, ×1.4; 6-Gully proletariat, 6a. Side view, 6b. Oral opinion, 6c. Suture, ×0.7, Lower Carboniferous, North America; 7-horned toad, 7a. Side view, 7b. Oral opinion, 7c. Suture, ×0.5, Middle Triassic in Germany; 8— Tibet ophiolite, 8a. Side view, 8b. Oral opinion, 8c. Lower Triassic suture in Tibet, × 0.7; 9— Heterophyllous cherry, 9a. Side view, 9b. Oral view of lower Jurassic in Britain: 10— Corynebacterium ovatum, 10a. Appearance, 10b. Suture, ×0.7, Upper Cretaceous, USA; 11-Upper Cretaceous Turrillites splendidus, shape × 0.7; 12-mylabris, 12a. Side view, 12b. Suture, ×0.5, Cretaceous, USA; 13— Hong Kong ITES Hong Kong, 13a. Side view, 13b. Abdominal visual field, ×0.7, Lower Jurassic in Hong Kong.
2. Lifestyle and morphological function analysis
Chrysanthemum stones are all marine, and the shape, size, thickness, rolling method, shell decoration and suture complexity of shells vary greatly, which may adapt to various marine environments. It is generally believed that those fish that are good at swimming in deep water are those with tight and flat shells, sharp and streamlined abdominal edges and smooth shell surfaces, while those with bulging abdomen and developed shell ornaments are not good at swimming. Some young shells of ammonites are different from adult shells, which may be due to different lifestyles at different stages of individual development. For example, Scaphites (Figure 4-43, 12) has swimming life in its young shell, but the life with hooks in its adult shell may be floating life. In addition, a few ammonites are benthic, such as Turrilites (Figure 4-43, 1 1), and their lifestyles are very similar to those of gastropods.
Chrysanthemum stone can adjust the gas and liquid content in the air chamber, control the ups and downs, and live in seawater with different depths, but it must be reinforced to ensure that the shell will not be broken due to pressure changes caused by water depth changes. The complexity of ammonite suture reflects the bending degree of the edge of partition wall. The more bends, the greater the contact surface between the partition wall and the shell wall, and the greater the strength of the shell. Therefore, it is considered that the ammonite with complex suture is swimming in deep water.
The shell decoration of chrysanthemum stone is also related to lifestyle, for example, the type of shell decoration of fast swimming is underdeveloped to reduce resistance; Cross ribs are used to strengthen the shell, and thorns are used to keep balance and resist foreign enemies.
3. Evolution
The ammonite evolved from Nautilus, and the earliest ammonite is the edgeless ammonite, which appeared in Devonian and is a primitive ammonite. Middle Devonian ammonite evolved from sessile ammonite, which was the most important ammonite in late Paleozoic, and flourished in Carboniferous and Permian. The ammonite evolved from the Permian forecourt ammonite, and developed in great quantities in Triassic. At that time, almost all ammonites were ammonites. At the beginning of Triassic, ammonite evolved from ammonite, and ammonite with shell decoration was extremely prosperous and important in Jurassic and Cretaceous. In the late Cretaceous, ammonites declined rapidly and eventually became extinct. To sum up, ammonites can be roughly divided into four development stages. The Devonian is dominated by ammonites, the Carboniferous and Permian are the prosperous periods of ammonites, the Triassic is characterized by ammonites, and the Jurassic and Cretaceous are the peak periods of ammonites.
The evolution trend of the above ammonites is mainly reflected in the following aspects: (1) the suture line is from simple to complex; The main body tube is changed from a backward extending main body tube to a forward extending main body tube; The shell shape changed from loose to spiral, and abnormal shell appeared; The shell mouth changed from abdominal curvature in late Paleozoic to abdominal sheath or abdominal process in Mesozoic; Shell decoration from scratch, from simple to complex.
Figure 4-44 Outline of Arrow Stone Inner Shell
(According to Schlock & Twenhoff, 1953)
Figure 4-45 Archean fossils
(quoted from Piveteau, 1952)
1-Triassic chytrid Timor on Timor Island, × 0.7; 2— Bemisia besina, ×0.7, Middle Jurassic, Europe.
(4) Sheath subclass
All cephalopods, except Nautilus, belong to the subclass Coleoptera, which is also known as the subclass Bibranchia because it has two gills. /kloc-More than 0/0 wrists, or 8 wrists with suction cups. Ink bag. Have an inner shell, or degenerate without a shell, also called Endo? Kochilia). They are all marines. According to the number of brachiopods and the characteristics of shells, it can be divided into Octopoda and Decapoda. Da) and sagitta. The most important fossil is the archer. The shell of arrow stone is fully developed and its structure is complex, which consists of three parts: sheath, closed cone and toenail (Figure 4-44). The sheath is mostly cylindrical or conical, consisting of fibrous calcite arranged radially, and its cross section is round, nearly square, kidney-shaped and oval. The back end of the sheath is pointed, and the front end is a hollow cone, in which a closed cone is embedded. The surface is generally smooth, with longitudinal abdominal or lateral grooves, and some with longitudinal ridges or ripples. The closed cone is conical and divided into many air chambers by partition walls. There is a body tube near the abdomen with a small spherical shell at the top, which is the initial growth part of the shell. Toe nail is a long and wide tongue-shaped protrusion, which grows on the back of a closed cone. Most arrow stone fossils are only preserved in their sheaths, and it is difficult to preserve closed cones and front nails. The shape of sheath, the shape of cross section, the characteristics of groove, the shape of sheath tip and the decoration of surface are the important basis for the classification of arrow stones.
Archean existed from Carboniferous to Eocene, but rarely in Carboniferous and Permian. Triassic began to develop and flourished in Jurassic and Cretaceous. It is a common fossil in Jurassic and Cretaceous marine strata. Abundant arrowheads have been found in Mesozoic marine strata in China, Tibet and Yunnan, such as Aulacoceras (trench arrowheads, Figure 4-45, 1) and Belemnopsis (similar arrowheads, Figure 4-45, 2).