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 Varisian (Varis) mountain formation processes, and ended with the beginning of the Alpine folding (the major last tectonic revolution).
In the Southern Hemisphere , the schism of the ancient mainland of Gondwana ended. In general, life in the Mesozoic era was characterized by relative calm. Mountain building processes were rare and short-lived.
The Mesozoic era lasted approximately 160 million years.
From a biological point of view, this era was a 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 named so because three different rock complexes are assigned to its deposits. These include the naper - upper, limestone - middle, continental sandstone - lower. The most characteristic are sandy-clay continental rocks (often with coal lenses), shales, sea limestones, gypsum, salts, lagoon anhydrides.
In the Triassic period, a connection of the southern mainland (Gondwana) with the northern continent (Laurasia) took place. Along with these changes in the distribution of land and sea, mountain building, the formation of new volcanic sites, renewal of the flora and fauna was quite intensive. However, only a few species have moved from the Paleozoic to the Mesozoic. According to researchers, all these factors are the result of large-scale disasters that occurred at the border of eras.
The next stage, which includes the Mesozoic era, is the Jurassic. It began about 200, and ended about 145.5 million years ago. The Jurassic period has become one of the most famous periods in the development of the planet.
At this time, gymnosperms and ferns were most common among plants. It is assumed that the environmental conditions were similar to the conditions of the Carboniferous period, since extensive coal formation was noted. The huge continent that existed in the Permian system and began to split in the Triassic system continued to decay. This process had a significant impact on the currents in the ocean, the amount of precipitation, climate and the living conditions of organisms in general.
The Jurassic period is considered "reptile time." Land was inhabited by dinosaurs. Plesiosaurs and ichthyosaurs lived in the seas, and pterosaurs lived in the air. Giant species began to form among the dinosaurs. Along with this, small insectivorous pterodactyls also existed. At the end of the Jurassic period, the accumulation of powerful layered layers of limestone - chalk began. Thus, a new stage arose.
The beginning of the Cretaceous period is characterized by some 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 breeds still growing today (for example, elm, oak, willow, maple). The Cretaceous fauna is basically similar to that developed in the Jurassic period.
The end of this stage was characterized by intensive orogenesis (mountain building) in East Asia, North and South America. Sedimentary rocks accumulated in the Andean geosynclinal for several periods, compacted and crumpled into folds. Thus, the Andes formed.
Volcanic activity intensified in many areas of the planet. The entire southern part of the Hindustan Peninsula was covered with lava (thus formed a large plateau "Dean"). At the end of the Mesozoic era, significant uplifts were noted on all continents.