The era is a large time period, a historical period. So called the system of chronology, as well as the beginning of this chronology. The entire history of our planet can conditionally be divided into long periods. Between themselves, they differ in certain climatic and geographical changes, as well as a significant breakthrough in the development of the animal and plant world. Many are interested in what eras are and what they are. Consider the main stages of the development of the Earth.
Archean era
At this time, our planet was formed, the period lasted about a billion years. There was no life on Earth yet, in the ocean chemical reactions took place between acids, alkalis, salts. The Archean era gave rise to protein matter. It was then that living organisms began to emerge.
Proterozoic era
The longest period of development of the planet, which lasted about 2 billion years. At this time, algae and bacteria develop, organisms acquire their own organs, they become multicellular. The era is a time period when something new appears, the Proterozoic stage was distinguished by the formation of iron ore deposits. This period is characterized by the fact that all life processes take place in the ocean.
Palaeozoic
This is a period characterized by a constant change in climatic conditions, it is divided into 6 stages. At this time, the flora and fauna are developing, many species of fish appear. Coniferous trees and ferns grow along the shores. Around the middle of the era, the first amphibians appeared in the form of reptiles, beetles, grasshoppers. The period is characterized by constant disasters, a change in the shape of the continents.
Mesozoic era
Stage consisting of the Triassic, Jurassic and Cretaceous periods. The Mesozoic era is the appearance of land and sea turtles, frogs, shrimps, new varieties of coral. The dominant position is occupied by reptiles and dinosaurs. In the middle of the era, the first representatives of modern birds and insects appear. In the Cretaceous period, the extinction of pterosaurs and dinosaurs occurred.
At this time, climatic conditions improve, as a result of which the earth is covered with greenery. On land, the first species of cypresses and pines, as well as flowering plants, appear. In the Mesozoic era, insects and representatives of the flora begin to cooperate. During this period, the continents take on new shapes and sizes; as a result of their split, islands form. The Atlantic Ocean is growing in size, flooding large tracts of land.
Cenozoic era
“How many years does the period in which humanity lives?” - Often people ask such a question. The Cenozoic era (it continues to this day) began about 66 million years ago. She distinguished herself by the appearance of modern birds, mammals, angiosperms and, of course, humans. By the middle of the era, almost all the main groups of the kingdoms of wildlife had already formed. At this time, steppes and meadows, new types of grasses, shrubs appear. Also in nature, the main types of agrocenoses and biogeocenoses are formed. A person begins to adapt to the environment, use nature to satisfy personal needs. It was people who later changed the organic world. The Cenozoic era consists of three periods: Paleogene, Neogene and Quaternary. It continues today.
The eras considered are divided by climatic and geographical features. But there are other chronological systems. For example, saying “our era,” many mean a stage that originates from the Nativity of Christ. Also, people distinguish industrial, technotronic and other periods that have distinguished themselves by something, changed people's perception of the world, and changed their attitude to living organisms.