Which one of the following characteristics is common among parrot, platypus and kangaroo ?

The common characteristic among the parrot (a bird), the platypus (a monotreme mammal), and the kangaroo (a marsupial mammal) is homothermy, also known as being warm-blooded or endothermic [t1][t2][t7]. Homothermy is the ability of an organism to maintain a constant body temperature regardless of environmental changes [t7]. While birds and mammals share this trait [t8], they differ in other aspects: parrots and platypuses are oviparous (egg-laying), but kangaroos are viviparous (giving birth to live young) [c2][c3][t4]. Regarding anatomy, parrots have toothless beaks and platypuses have toothless jaws as adults, but kangaroos possess complex dentition [t5][t6]. Additionally, while all three are chordates and possess a post-anal tail at some stage, its functional nature and structure vary significantly across these diverse groups. Therefore, homothermy is the only unifying physiological trait among the three [t3].

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 12: Animal Diversity of India > 12.3.r. Egg Laying Mammals > p. 190
2. [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 4: BIODIVERSITY > x) not evaluated (ne) > p. 16
3. [3] https://dpbck.ac.in/wp-content/uploads/2023/06/3.-Vertebrate-Kotpal_compressed.pdf