Which one of the following characteristics is not shared by birds and mammals? (a) Viviparity (b) Warm blooded nature (c) Ossified endoskeleton (d) Breathing using lungs
Option A All birds are oviparous while all mammals except Ornithorhyncus (duck billed platypus) and Echidna or Tachyglossus (spiny anteater) are viviparous.
