Mammal

Mammals are a class of vertebrates that includes over 4,000 species. Among other characteristics, mammals are distinguished by:

- a constant body temperature;

- hair;

- the fact that they suckle their young;

- the presence of a lower jaw, formed by a single bone.

The first mammals appeared during the early Secondary Era. They were not very diversified during the time of the dinosaurs. After the Cretaceous-Tertiary crisis, mammals began to proliferate and dominate the animal world.