Mammals are a class of vertebrate animals, whose females are characterised by the possession of mammary glands.
They are divided into three main taxa, monotremes, marsupials, and placentals.
Apart from 5 species of monotremes, that lay eggs, all other species give birth to live young.
There are currently nearly 5,500 species of mammels on the planet today.
The Mammalian line of descent commenced at the end of the Carboniferous Period, 290 million years ago, when one line of evolutionary divergence became reptiles, and the other mammals.
The demise of the Dinosaurs, approximately 65 million years ago, allowed the mammals to thrive, and they proliferated throughout the world.
And, here we are today, as the dominant species on the planet.
Had the Dinosaurs not perished things could be a little different !!