A mammal is a vertebrate animal belonging to the class Mammalia. Mammals are distinguished by several unique traits, including the possession of mammary glands that produce milk for nourishing their offspring, a neocortex region in the brain, the presence of fur or hair, and three middle ear bones. These distinct characteristics set mammals apart from reptiles and birds, with whom they share a common ancestor that diverged during the Carboniferous Period, more than 300 million years ago.
Currently, scientists have identified approximately 6,400 living species of mammals, each classified into one of 29 different orders.
