What is common between parrot, platypus and kangaroo?

All three animals are homeothermic (warm-blooded), meaning they can maintain a constant body temperature regardless of environmental changes. Parrots are birds (Aves), while platypus (monotreme) and kangaroo (marsupial) are mammals. While platypus is oviparous (lays eggs), parrots are also oviparous, but kangaroos are viviparous. Only homeothermy is shared by all three.