What Do Paleozoic, Mesozoic, and Cenozoic Mean?

The Mesozoic is one of the three geological ages of the Phanerozoic, which can be divided into the Triassic, Jurassic, and Cretaceous. The Mesozoic was first established by the Italian geologist Giovanni Arduino, at that time called the Secondary, relative to the modern Tertiary.

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Mesozoic mass extinction

The Cretaceous extinction event at the end of the Mesozoic era resulted in 50% of extinction, including all dinosaurs. Most scholars believe that a comet hit the earth and caused extreme climate change. Many animals, especially cold-blooded animals, cannot adapt to low temperatures and become extinct. But why cold-blooded animals such as crocodiles survived at the time is still unanswerable. ^[4]

Mesozoic biological evolution

Paleozoic trilobites

The Mesozoic was a world of reptiles on land in the early and middle Mesozoic era, but primitive mammals and primitive birds had already appeared at this time, and flourishing angiosperms also developed at this time. The emergence of a large number of feathered dinosaurs, early birds, ancestral groups of modern insects and angiosperms in the middle and late Jurassic period indicates that this period is an important period of change. The late Cretaceous mass extinction in the late Mesozoic era caused the prosperous reptiles to decline, and new species began to occupy the niche left by reptiles. A new era, the Cenozoic, was born.

• Triassic

An extinction event that occurred at the end of the Permian era, exterminating most of the organisms on the earth at the time, and many organisms began to adapt to radiation after the event. Millions of years after the end of the Permian extinction event, large main dragon reptiles have become Mesozoic terrestrial dominant animals, including: dinosaurs and pterosaurs; reptiles in water include: ichthyosaurs, pinosaurus, sea dragons class.

Time and space shuttled to the Triassic, at which time the earth had entered the Mesozoic. Compared to the old days (Permian Permian), it is more full of life. In the ancient ocean, the ferocious carnivorous Sastosaurus is preying on other marine prey. For it, the Triassic ocean became its "Free restaurant". About 70% of the time in the entire Mesozoic era, it has played an important role in the ocean. There are no four oceans at this time. The land is a complete joint ancient land that is connected and integrated in today's seven continents. Gasmatosaurus (living in the early Triassic, a huge amphibious, carnivorous, earliest ancestor of modern crocodiles and American crocodiles). In the northern part of the pan-continent, a large group of water dragon beasts is slowly moving south. This is a kind of mammal-like reptiles. They look like dinosaurs that appeared 30 million years later, but unlike dinosaurs, these early mammal-like reptiles and our human direct ancestors, mammals, are closer. Some, they are not so closely related to lizards and crocodiles. Of course, it is a direct blood relative of modern mammals, including humans, and evolved from the Permian burrowing animal Bidtozoa. When the Permian species was extinct, it was due to its small size and strong vitality. The forelimbs excel at digging and digging holes, which escaped the disaster and survived.

Deep in the forest, it seems that an inconspicuous species is destined to completely change the face of future life on Earth, and start a new era of reptiles, laying the foundation stone for the birth of the most powerful "empire" in history. This time is about 240 million years ago. In our South Africa today is a dense jungle, a paradise for predators and herbivores. Here, a small carnivore that is less than a foot tall, can run on its hind legs, is fast, and specializes in hunting insects. The new bus crocodile is busy in all corners of the jungle. It has developed hips in the legs. The bone makes it have a strong jumping ability, which can accurately and effectively capture dragonflies or other insects in flight, and can easily avoid the threat of predatory natural enemies at lightning speed. Because of its small body and sensitive "hands", it has become an unparalleled predator in the jungle. However, no one would have thought that the little guy who ran predatory in this early Triassic jungle would dominate the entire world in more than 37 million years and dominate the land, sky and ocean of the earth. They are the dinosaurs (meaning horrible lizards) that we humans know today as Mesozoic earth overlords. The ace tyrannosaurus rex, vegan giant diplodocus, brachiosaurus, and various large sauropod reptiles in the later dinosaur family have evolved from this elf new bus crocodile, which is less than one foot tall. It is the common ancestor of dinosaurs and crocodiles.

• Jurassic

Mesozoic dinosaurs (5 photos)

Time then continued through the Triassic, entering the Early Jurassic, about 200 million years ago. Since then, the era of "Dragon World" has begun. From the early Jurassic to the late Cretaceous, 140 million years (this is almost 150 times the life of humans on the earth), the earth has been "the world of the dragon". Reptiles ruled the land, the sky, and the ocean. They traveled freely as if they were unmanned, because they were the hegemons of the world at the time. Just as our human beings are on the earth today, they belong to the proud of the earth and the king of the earth. Except for a major natural disaster, it is almost impossible to get it out of the earth's stage, and there is no chance for a species to replace it. This period is called the golden age of reptiles, also known as the dinosaur age. In that "dragon world", there is no room for development or space for any other species. Early mammals could only live in burrows for their own safety, and often sneaked out to find food to eat at night. In the Jurassic period of the Mesozoic, the earth's climate was extremely warm and humid. There was no concept of four seasons in a year. Only the dry season and the rainy season. The prototype of the first four oceans. Mesozoic climatic conditions are particularly adapted to plant growth. In the middle and late Jurassic period, the earth was widely covered with extremely lush gymnosperms and ferns. This is also a rich food paradise for vegetarian dinosaurs. Every year before the rainy season, beak-billed pterodactyls living in today's South America fly across the Atlantic Ocean to today's west coast of France in search of its opposite sex for mating. At this time, the Atlantic Ocean was only 300 kilometers wide, and male pterosaurs would peck fish jumping in the sea from time to time to supplement their physical strength while flying across the ocean, and there was always the danger of being swallowed by the terrifying marine killer Hydra. Pterodactyl was exhausted by the time he reached his destination. It often takes more than a week of rest before looking for your spouse.

• Cretaceous

About 70 million years have passed, and the Earth has entered the Cretaceous era, and there is still a "weak meat and strong food" on the land. At this time, two fierce Tyrannosaurus rexes are fighting for a bit of a pseudo-monarch. This is the best known Cretaceous cold-blooded killer today. Because of its large size and the sharp chews of its powerful jaw, the food it bites is equivalent to the volume of a whole strong boar. However, not all herbivorous dinosaurs will become "dinner dishes" of Tyrannosaurus Rex. The Earth's climate in the late Cretaceous has been worse than before, and a large number of plants have died due to long-term drought. The number of herbivorous dinosaurs plummeted because they couldn't find enough food to feed their hunger. With the extinction of vegetarian dinosaurs, natural carnivorous dinosaurs have also cut off their food sources. However, "full water overflows, and full moon loses." Once everything in the world has reached its peak, it will go downhill. The dinosaur family has come to an end at this time. The earth seemed to herald a period in the future where a "massacre" at the end of the Permian period would be repeated. About 65 million years ago, an asteroid named Yucatan struck about 1 km in diameter. In today's Mexico. The explosive explosion of tens of thousands of atomic bombs occurred in an instant. This "sky and earth collision" destroyed many lives on earth and ended the dinosaur era.

Cretaceous extinctions occurred at the end of the Mesozoic, and 50% of all organisms, including all dinosaurs.

Climate change in the late Jurassic and Cretaceous periods caused another radiation adaptation. Diversity of the main dragon species peaked during the Jurassic period, and birds and placental mammals also began to emerge and develop. Angiosperms also began to develop in the early Cretaceous period, and they began to appear in tropical regions. The global temperature of the Cretaceous allowed angiosperms to be distributed to the polar regions. At the end of the Cretaceous period, angiosperms have become large-scale dominant plants in many regions. If calculated in terms of biomass, the dominant plants in various places are still cycads and ferns until the end of the Cretaceous extinction event.

Some scientists believe that some organs of insects are quite suitable for angiosperms, especially mouthparts, and that insects and angiosperms begin to diversify at the same time. However, the appearance of insect mouthparts was earlier than that of angiosperms and earlier than the time when insects began to diversify. Therefore, insect mouthparts evolved based on other reasons.

In the course of the Mesozoic, the early large animals gradually decreased, while the number of small animals gradually increased, including lizards, snakes, and possibly mammals and primates. This tendency was exacerbated by the end-Cretaceous extinction events, with large host dragons disappearing, while birds and mammals continue to survive to this day.