The Mesozoic era (the era of middle life) began 250 million years ago.
It is subdivided into three periods: Triassic, Cretaceous and Jurassic.
At the beginning of the Mesozoic, gymnosperms flourish. Unlike ferns, horsetails, and lymphoids, gymnosperms do not depend on water to reproduce.
In the second half of the Mesozoic era, angiosperms appeared. An important aromorphosis in them was the formation of the fruit, which protects the seed and attracts animals.
The second aromorphosis of angiosperms is the appearance of a flower, which made it possible to carry out sexual reproduction with the help of insects. These aromorphoses led to the rapid development of flowering plants.
An increase in the species diversity of flowering plants promoted an increase in the species diversity of insects.
Cartilaginous and bony fish are widespread in the seas. The flowering of cephalopods begins. But the greatest flourishing is achieved by reptiles. Some of the aquatic reptiles reached gigantic proportions – several meters in length and weighing tens of tons.
Reptiles also dominate on land. They occupy all natural environments. Herbivorous reptiles were of different sizes (more than 20 m in length) and different devices for protection. Carnivorous reptiles also reached impressive sizes. Some of the reptiles adapted to flight and took over the air.
The flourishing of reptiles was possible thanks to the warm climate of the Mesozoic era.
Towards the end of the Mesozoic era, the Earth’s climate becomes colder and drier. Reptiles are unable to maintain a constant body temperature. They were replaced by warm-blooded birds and mammals.