The most ancient animals, such as amphibians and reptiles, most often could not take care of their cubs, fighting for their own survival. With the advent of mammals, everything has changed.

At the end of the dinosaur era, the first animals were born that were able to give birth to live cubs and feed them milk. These were the ancestors of mice, squirrels, cows, horses, monkeys and many other animals, as well as humans.

Interesting fact: fish, amphibians, reptiles, dinosaurs, bird insects - all these living creatures arose on Earth before mammals. They reproduced themselves by laying eggs or eggs. This is an ancient, but far from the most perfect way of reproduction.

The end of the dinosaur era

Some scientists believe that perhaps the first mammals were rodents, which accelerated the extinction of dinosaurs. They found their eggs very tasty and destroyed them before the cubs could be born.

The first mammals were small and looked like our small rodents. They had a great advantage over the larger animals that lived on Earth at that time: they were more intelligent and dexterous. One of the first mammals was morganukodon.

Mammals appeared about 50 million years ago. For details on when mammals appeared, see our article: When did mammals appear?

Ferocious mammals

Gradually, some species of predatory mammals began to appear, which were very ferocious. However, they remained mostly small in size.

The struggle for existence allowed the survival of more agile and strong animals.Some of their species have not changed much until today, while others have changed very much.