keeping them for a while

Later, other mammals began to give birth to their live young, keeping them for a while in a bag or pouch until they were able to walk alone Princess Hair; it is what happens in the marsupials, like the kangaroo or the koala.

And finally, evolution led to the development of the placenta, which allowed the offspring to develop better in the womb; at birth they are able to move alone and feed on the milk produced by the breasts.