The Mesozoic era is considered a transitional stage in the development of the planet. Some geologists call it the "biological and geological middle ages."
The Mesozoic era began at the end of the Variscian (Varissian) mountain-building processes, and ended with the onset of Alpine folding (a large last tectonic revolution).
In the southern hemisphere ended the split of the ancient continent of Gondwana. In general, life in the Mesozoic era was characterized by relative calm. Mountain building processes were rare and short.
The Mesozoic era lasted approximately 160 million years.
From a biological point of view, this era wasthe time of transition from primitive, old forms to more progressive, new ones. The world at that time was much more diverse than in the Paleozoic, and the flora and fauna were significantly updated.
Mesozoic era. Periods
There are three stages in this era.
The first - the Triassic - is so named because of the fact thatIts sediments include three different rock complexes. These include the naper - upper, limestone - medium, continental sandstone - lower. The most characteristic are sandy-clay continental rocks (often with carbon lenses), shale, sea limestone, gypsum, salt, lagoon anhydrides.
В триасовый период произошло соединение южного mainland (Gondwana) with the northern continent (Laurasia). Together with these changes in the distribution of land and sea, mountain building, the formation of new volcanic areas, the renewal of flora and fauna took place quite intensively. However, only a few species moved from the Paleozoic to the Mesozoic. According to researchers, all these factors are the result of large-scale disasters that occurred on the border of epochs.
The next stage, which includes the Mesozoic era - the Jurassic. It began about 200, and ended about 145.5 million years ago. The Jurassic period became one of the most famous periods in the development of the planet.
At this time, the most common amongplants received gymnosperms and ferns. It is assumed that the environmental conditions were similar to those of the Carboniferous period, since extensive coal formation was noted. Existed in the Permian system, which began to crack in the Triassic system, a huge continent continued to decay. This process had a significant impact on the currents in the ocean, the amount of precipitation, the climate and the living conditions of the organisms as a whole.
Юрский период считается "временем пресмыкающихся".Land was inhabited by dinosaurs. Plesiosaurs and ichthyosaurs lived in the seas, pterosaurs were in the air. Giant species began to form among the dinosaurs. At the same time, small insectivorous pterodactyls existed. At the end of the Jurassic period, accumulation of thick layered layers of limestone - chalk began. Thus, a new stage has emerged.
The beginning of the Cretaceous period is characterized bysome large-scale events in the formation of the organic world. At this time, the first flowering plants began to appear, the fossil remains of which are represented by wood and leaves of species growing today (for example, elm, oak, willow, maple). The fauna in the Cretaceous period is basically similar to the one that developed in the Jurassic period.
The end of this stage was characterized by intenseorogenesis (mountain building) in East Asia, North and South America. Sedimentary rocks accumulated in the Andean geosyncline over several periods, compacted and creased into folds. Thus, the Andes were formed.
In many areas of the planet has intensifiedvolcanic activity. The entire southern part of the Indian subcontinent was covered with lava (this was how the large Deccan plateau formed). At the end of the Mesozoic era, significant uplifts were observed on all continents.
