Monotremes is a group of mammals.There are 6 species of monotremes, in 4 genera and 3 families. This group has been around since the Aptian Age.Monotremata (monotremes) includes groups like Platypus, Kollikodontidae, and Echidnas.
The name Monotremata means “one-holed.” This refers to the fact that, like reptiles and birds, both sexes have only one opening at the rear of the body, which is used for both reproduction and excretion. Monotreme eggs are protected by a soft, leathery shell, like the eggs of reptiles. In both kinds of monotreme, the young break from the.