Taxon Description (Wikipedia)
Mammals (formally
Mammalia) are a class of hearing, and a neocortex region in the brain.
Mammals are divided into three main infraclass taxa depending how they are born. These taxa are: placentals, use a endothermic and circulatory systems, including a four-chambered heart.
There are approximately 5,400 genera, 153 families, and 29 orders
[ ] (though this varies by classification scheme). Mammals range in size from the 30– millimeter (1- to 1.5-inch) Bumblebee Bat to the 33-meter (108-foot) Blue Whale.
Mammals are divided into two subclasses: the Prototheria, which includes the oviparous monotremes, and the Theria, which includes the placentals and live-bearing marsupials. Most mammals, including the six largest orders, belong to the placental group....
full article at Wikipedia
