Why does the kangaroo belong in mammal group?

Answer 1

The koala is in the class Mammalia because it is a mammal. It is a warm blooded vertebrate with fur, like most land-dwelling mammals; it breathes air through its lungs (as opposed to gills, which fish use); above all, it feeds its young on mothers' milk, which is the defining characteristic of a mammal.

Answer 2

Kangaroos are marsupial mammals because they give birth to live young that then crawl into the mother's pouch to continue nourishment and growth.