Mammals are divided into three groups:

  • Monotremes are mammals that lay eggs, like a bird. They live in Australia and New Zealand. The platypus belongs to this group.
  • Marsupials are mammals that raise their young ones in a pouch in their bodies.
  • Placentals are the largest group of mammals. The babies grow inside their mothers until they are ready to be born. Humans are placentals.



Platypus
Image:Stefan Kraft, CC BY-SA 3.0, via Wikimedia Commons