readx;?“ In the early Silurian period (about 443 million years ago - 419 million years ago), transgressions were formed everywhere, and the middle transgressions reached their peak. Pen @ fun @ pavilion wWw. ｂｉｑUｇE。 ｉｎｆｏ

In the late Silurian period, the earth's crust moved strongly, the PaleoAtlantic Ocean closed, and some tectonic plates collided, resulting in the rise of some trough folds, and the land began to rise significantly from the sea, and the continental area expanded significantly.

In the late Silurian period, the naked fern among terrestrial plants appeared for the first time, and the plant finally began to develop from water to land, which was a major event in biological evolution. Previously, all living things lived in water, but during the early and middle Ordovician and Silurian periods, the sea engulfed large areas of land with a large number of marine life. In the late Silurian period, when the land was uplifted and the sea transgression subsided, a large number of marine organisms could not return to the ocean and were abandoned on land. Most of these creatures died, only a small fraction of them survived, and they developed into later terrestrial organisms. The original gymnofern (evolved from green algae) emerged, a plant type that transitioned from aquatic to terrestrial.

Jawed shield fishes and spiny fishes appeared in the Silurian period. Jawless species flourished in the Silurian period. However, because they are jawless and have a backward lifestyle, they can only feed on the food mixed in the water that flows into their mouths, so in the struggle for survival, they are unable to compete with the new jawed fish and are gradually declining. This was a major event in the evolution of vertebrates, and fish began to conquer the waters, creating the conditions for the great development of fish in the Devonian period.

During the Devonian period (about 419 million years ago - 359 million years ago), the northern paleocontinent was warm, and the Arctic region was in a temperate climate until the present-day Arctic.

In the early Devonian, lycopodium plants appeared, and most of them were herbaceous types with simple forms and small individuals. In the middle of the Devonian, primitive wedge-leaved plants, the most primitive true ferns, and bryophytes appeared. New eumorphic ferns, seed ferns, and primitive gymnosperms emerged in the late Devonian period, and gymnosperms were on the verge of extinction.

Among the invertebrates, brachiopods, tetra-shot corals, stick stones, odontolites, prismatic stones, and Poseidon stones are the main ones, while the nautilus species are greatly reduced, and most of the monoliths are extinct, and only a small number of representatives of the monolithidae remain.

Devonian fishes were quite abundant, and various types of fish appeared, which is known as the "age of fishes".

Insects appeared in the late Devonian period. Its ancestors lived in water. At the same time, it is also the common ancestor of rings and hookpods. At the end of the Devonian period, winged insects appeared.

Amphibians appeared in the late Devonian period. Amphibians evolved from fish, which can be active on land and swim in water, and cannot live without water.

About 365 million years ago, at the end of the Devonian period, there was another extinction event, during which there were two peaks, 1 million years apart, and marine life was devastated. This extinction event was time-sensitive, large-scale, and affected by a wide range of phyla.

Marine life has been devastated, with more than 70 families of marine animals extinct and 82% of marine species extinct, more serious than terrestrial life. The extinct families accounted for 30% of the total number of families at that time,

The most affected by this mass extinction are those that live in warm waters.

At that time, almost all corals in the shallow sea were extinct, coral reefs in the shallow waters of the equator were all extinct, deep-sea corals were also partially extinct, foraminifera were almost all extinct, bamboo stones were all extinct, phytoplankton extinction rate was also more than 90%, three major groups of brachiopods were extinct, jawless fish and all shield fish were seriously affected.

Terrestrial plants, as well as freshwater species, are also affected. The reason for this is also the cooling of the Earth's climate and the retreat of the oceans, this time it is still the expansion of the Antarctic (Gondwana continent) ice sheet caused by the Ice Age, and the oxygen content in the shallow sea area has also decreased, possibly due to plate drift, so that the organic matter released by the exposed shallow continental shelf is released into the water, which greatly consumes the oxygen in the water, and at the same time releases a large amount of heat and makes the water temperature in the shallow sea rise rapidly, beyond the limit that marine life can bear.

In this case, the largest loss is in the original warm water area, which is in the hottest part of the planet, and reheating seriously disrupts the ecological balance. And the special on land, although it has an impact, but the impact is limited.

Carboniferous (about 359 million years ago - 299 million years ago)

It was not until the early Carboniferous period that the Gondwana continent was formed, which included present-day South America, Africa, Australia, Antarctica, the Indian Peninsula and the Arabian Peninsula, as well as the Himalayas in Central and Southern Europe and China. The unified Gondwana continent and the lauya continent to the north are separated by the ancient Tethys Ocean, which is narrow in the west and wide in the east, and shaped like a trumpet.

The Carboniferous climate was very differentiated, and the northern Laoya ancient continent had a warm and humid climate, and many swamps and lakes appeared on the land. The Gondwana paleocontinent is an Antarctic region that has become a cold continental glacial sedimentary environment. Climatic zoning has led to the formation of zoological divisions of animals and plants.

Invertebrates are dominated by corals, brachiopods, and ammonites; trilobites are mostly extinct, leaving only a few genera and species; and emerging species of trilobites have emerged.

Amphibians reached their peak and are known as the Amphibian Age (including the Carboniferous and subsequent Permian). In the late Carboniferous period, the interior of the Gondwana paleocontinent was differentially elevated, forming intracontinental rifts.

The Late Carboniferous Laoa paleocontinental plants developed further in warm and humid climates. Ferns (spore plants, water-loving) thus quickly fill the land, forming the most primitive forests. This environment with both plants and water provides the best opportunity for herbivorous insects to survive and reproduce.

Insects are further developed. In the competition for survival, insects begin to evolve in the direction of small size, less food and strong fecundity.

Reptiles first appeared in swampy forests during the late Carboniferous period. Reptiles belong to the quadruped class Amniotic and are the general term for all species of the sauromorphs and zygosida except birds and mammals. Because its embryo develops in an amniotic egg laid on land, its reproduction and development are free from dependence on the external water environment, and it is a true terrestrial vertebrate. This is very different from amphibians.

Reptiles are divided into the subclass Porous, the Subclass Hypopore, the Subclass Modular, the Inferior Class Lepidon, and the Lower Class of the Primosaurus. The subclass Inferior Hole is divided into Coilosaurus and Orioporeidae.

Cuposaurus in the class Aforamorphus is the ancestor of all reptiles that are present.

Also known as mammal-like reptiles, the subclass Inferior Hole contains all the mammal-related species of amniotes, divided into Disc Saurus and Oriodoreda, and is the first group of tetrapods with different teeth, including canines, molars, and incisors.

Coilosaurus: An early mammal-like reptile that was one of the first reptiles to appear in the late Carboniferous period.

The progenitor of the order Coilosaurus is the earliest subclass of the lower hole subclass. Coilosaurs were the first amniotic animals to dominate the Earth's land, and they dominated the Late Carboniferous period. Coilosaurus is bulky, has lying limbs, is cold-blooded, and has a small brain. They were the largest animals on land of that era, reaching up to 3 meters long.

At the end of the Carboniferous period, the Xiaoice period occurred. The Gondwana Continent in the south was the Antarctic at the time, and the ice sheet extended over a large area during the glacial age. The Ice Age made the warm and humid climate of the northern Lauya continent dry and cold. The number of ferns, which prefer warm, humid climates, is greatly reduced, while gymnosperms (seed propagation) develop more quickly, which provides a food source for the development of reptiles. So reptiles and gymnosperms were able to thrive in the ancient continent of Laoya, because they are a new generation of plants and animals that are truly free from the influence of water.

The next chapter introduces the Permian!

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