The peak of the dinosaurs (about 208-146 million years ago):

The Jurassic was the heyday of dinosaurs. At that time, in addition to dinosaurs on land and ichthyosaurs in water, pterosaurs and birds also appeared one after another. In this way, for the first time, vertebrates occupied the three major ecological fields of land, sea and air. The Jurassic turtles have flourished, and the Chinese turtle and the Tianfu turtle are its representatives at that time.

Dinosaurs rule the land. Over the course of more than 55 million years, they developed into herbivorous and carnivorous dinosaurs, ranging from small chickens to tall buildings. At the same time, the single continent on Earth decomposes into two continents, and the flora and climate become more diverse. But the earth is still warm, and there is no grass or flowering plants.

Fossils of birds from the age of dinosaurs are scarce, but Archaeopteryx shows many of the characteristics of carnivorous dinosaurs, leading most scientists to believe that it evolved from dinosaurs.

The last flourishing of dinosaurs (about 146 million to 65 million years ago):

The Cretaceous period was the last period of the Mesozoic Era, when dinosaurs were still flourishing and evolved the last branch of dinosaurs, the ceratosaurus. But by the end of the Cretaceous period, due to abrupt changes in the environment, all dinosaurs, as well as ichthyosaurs and pterosaurs, were all extinct. The reptiles, which had been dominant for a while, have since collapsed and withdrawn from the stage of history, and only a few groups such as crocodiles, turtles, snakes and lizards have survived this hurdle and remain to this day. Birds are one of the vertebrates that have had the greatest success in moving into the air.

Birds originated from the alveolar tooth class of reptiles. Many people have gone a step further to believe that birds are descendants of dinosaurs. The world's first bird is Archaeopteryx, which was found in Germany.

To date, only seven skeletal specimens have been found. Except for its feathers, this bird bears a slight resemblance to some small dinosaurs. Therefore, this 140 million-year-old (late Jurassic century birds) are also the most primitive birds. The Early Cretaceous (about 130 million years ago) was the period when birds first flourished.

The bird fossils found in Liaoning, China, are the richest, most complete and most diverse birds in the world during this period. During this period, birds were smaller in size, and their flight ability and arboreal ability were much higher than those of Archaeopteryx.

The Cretaceous period was the last epoch of dinosaur life and a period of great changes in the Earth's landscape. After reaching record heights at the surface of the sea, the shape of the various continents was very similar to that of today. Flowering plants appeared, as did many insects – from bees to ants. Giant lizards swim in the ocean with giant sea turtles.

In the air, pterosaurs spread their wings up to 12 meters. On land, dinosaurs dominated, surpassing all previous types in size and shape. Herbivorous dinosaurs grew up to 100 tons, and carnivorous dinosaurs reached a body length of more than 12 meters.

Mammals have been around since the age of the dinosaurs. For millions of years, they were primitive and small. Some of them may lay eggs. Mammals began to change during the Cretaceous period.

Nearly 70 million years ago, mammals diverged into two main groups. One is placental mammals, whose newborn cubs are well developed. Another group of mammals, marsupials, give birth to tiny cubs, which crawl into their mother's pouch to feed.

These two taxa still exist today, but their early species became extinct long ago. The placental mammals of the late dinosaur era included the earliest primates. Monkeys, apes, and humans are the primates of today. But the earliest primates were mouse-sized animals, such as the Pegaturi monkey.

Scientists can distinguish primates based on molars, which look a lot like the teeth in the back of modern primates. The Pegaturi monkey was one of the first primates. It is about 10 cm long and may feed on insects.

Cretaceous extinction events:

65 million years ago, dinosaurs disappeared from land, as did many other types of animals in the sea and in the air, including giant marine reptiles and flying reptiles.

Scientists have come up with a variety of theories to explain the extinction of the dinosaurs. The popular conclusion is that a huge asteroid has hit the Gulf of Mexico. The impact produced a huge tsunami that swept across the globe and caused multiple fires. Smoke and dust obscured the sky, darkened the sky, and blocked sunlight, making the earth cold. Volcanic eruptions can also produce the same results. Many animals are unable to adapt to weather changes. However, birds, mammals, crocodiles, and many others survived.

Evidence for this hypothesis also comes from an amino acid found in sediments from 65 million years ago found around the world. This amino acid contains a large amount of iridium, which is abundant in some celestial bodies, but should not exist at all on Earth. This iridium-rich layer has been found in many parts of North America, Europe and Australia, and was also found in the Gamba region of Tibet a few years ago.

Some scientists believe that the explosion wiped out all the dinosaurs. But some scientists believe that only 70% of the dinosaurs went extinct at the time, and that other dinosaur species narrowly escaped the catastrophe before gradually becoming extinct over the next few million years.

This latter claim is not unreasonable, as some dinosaur bones have still been found in the strata formed after this event 65 million years ago. For example, the remains of dinosaurs have been found in strata around New Mexico 60 million years ago. Fossils of Triceratops have also been found in the Cenozoic tundra of Alaska.

These phenomena seem to indicate that after the Big Bang caused by the asteroid impact on the Earth, there were still some dinosaurs who struggled to live for millions of years before finally becoming extinct because they did not adapt to the new climate and environment.

The Mammalian Era:

Tertiary (Te

tia

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IOD) began 65 million years ago and extended to about 1.8 million years ago. The important biological groups of the Tertiary are angiosperms, mammals, birds, bony fishes, bivalves, gastropods, foraminifera, etc., which are very different from the biological world of the Mesozoic Era, marking the advent of the "modern biological era".

Angiosperms were extremely abundant in the Tertiary period. Except for the pine and cypress, which still occupy an important position, the rest of the gymnosperms tend to decline. Ferns have also been greatly reduced and their distribution is mostly confined to warmer regions. The plants of the Tertiary period have obvious zoning phenomena, and there are many microscopic aquatic algae fossils in the strata.

The changes in vertebrates are mainly manifested in the decline of reptiles, which have been replaced by mammals, birds, and bony fishes, which have risen and flourished at a high level. In the early part of the Tertiary Period, there were still ancient and primitive mammals, and in the middle period, the ancestors of modern mammals appeared successively and gradually replaced the ancient and primitive mammals, and in the late Tertiary Period, the modern mammal fauna was gradually formed, and it was a period of flourishing artiodactyls and proboscis species. Horses, in particular, evolve very quickly.

At the end of the Mesozoic Era, marine invertebrates had obvious rise and fall. Ammonites were completely extinct, arrowstones were in extreme decline, and bivalves, gastropods, foraminifera, hexagonal corals, sea urchins, bryozoans, etc., flourished further. The foraminifera that appeared in the Tertiary were widely distributed and evolved rapidly, which is of great significance for the division and comparison of the marine Tertiary series.

In addition, their ecozonation has been applied to determine changes in water depth in sedimentary basins. Radiolaria among protozoa also flourished in the Tertiary and occupy a prominent place in deep-sea research. Bivalves developed greatly in the Tertiary period, and gastropods entered their peak period in the Tertiary period.

Terrestrial invertebrates are mainly bivalves, gastropods, and mesomorphs, and the terrestrial tertiary can be divided according to the changes in their assemblage in different periods.

About 50 million years ago, primates evolved in a radial shape, and higher primates were differentiated from the lower primates protomonkeys.

Between 33 million and 24 million years ago, apes were born. The earliest Australopithecus proto-ape and Egyptian apes found in Egypt already possessed some of the traits of anthropoids, and later Australopithecus fossils and forest apes were widely distributed and found in Asia, Europe, and Africa. The proto-Consul ape of East Africa is already an ape, the ancestor of humans and African apes.

The above australopithecus are all forest animals, walking on all fours, and belong to the group of apes climbing trees. There are two groups of extant apes, African apes (gorillas, chimpanzees and humans) and Asian apes (gibbons and orangutans), and there is a clear boundary between these two groups, which apparently diverged between 12 million and 15 million years ago.

Between about 10 million years ago and about 380 or 2 million years ago, there are two types of fossil representations of transitional periods. One is Ramaucus and the other is Australopithecus.

The first humans are referred to in anthropology as "fully formed man". Paleoanthropologists in China divide this process into two stages: apes and Homo sapiens, each of which is divided into two periods, early and late.

2.5 million years ago, the climate in tropical Africa began to deteriorate, and ice ages hit from the Northern Hemisphere. As the climate became more and more arid, the savannah began to gradually turn into a shrub savannah, and most of the australopithecus disappeared. There are two exceptions, one is that in some areas the savannah remains, where Australopithecus survives, such as Australopithecus homo and two stout species.

More importantly, some Australopithecus groups used their ingenuity to invent some successful defense mechanisms that could only be speculated about, such as throwing stones, using primitive weapons made of wood and other plant materials, and possibly campfires in the wild.

In fact, it was the descendants of these Australopithecus that survived and thrived, eventually evolving into a genus of humans, moving from tree-dwelling bipedal walking to terrestrial living and bipedal walking.

Some of the things that Liu has survived in the historical evolution have dissipated like a cloud of smoke, while some of the causal cycles have generated the current world. As in many historical times, Hua Feng faintly felt that after this "doomsday crisis", there might be greater challenges waiting for them, which was far greater than this crisis that could be called the survival of mankind.