General Characteristics of Class Mammalia
Mammals are the most evolved and adapted of the five Chordate classes. They include around 5000 species placed in around 26 different orders. Mammals are divided into 3 different major groups according to their embryonic development. Monotremes, although there are only 3 known living species (e.g. the platypus), are ovoviparous, but still suckle their young from simple mammory glands. …
