Question

Which one of the following characteristics is not shared by birds and mammals?
A. Ossified endoskeleton
B. Breathing using lungs
C. Viviparity
D. Warm blooded nature

Answer 1

Eggs are laid by all birds, some very colourful or marked with spots. The developing embryo derives nutrients from the yolk inside the egg and the albumin, the white of the egg.

Complete Answer:
Animals that have a backbone are known as vertebrates. A significant number of vertebrates actually live on Earth and, based on their physiological and anatomical characteristics, they are divided into 7 groups and they are aves, mammalia, reptilia, agnatha, amphibia, osteichthyes, and chondrichthyes.

Now, let us find the solution from the options-
- An endoskeleton consisting of bones is classified as an ossified endoskeleton. Many organisms have an endoskeleton purely made of cartilage and bones such as birds, bony fish, mammals, and reptiles. Bones are mainly composed of calcium and phosphates and serve the purpose of supplying an adequate structure for the body. Therefore, option A is the characteristic that is present in both mammals and birds.
- One of the species that is capable of respiration through the lungs is mammals. They are primarily terrestrial and there are marine ones as well. Birds can also breathe through lungs. Therefore, option B is the characteristic that is present in both mammals and birds.
- Between birds and mammals, viviparity is not shared. Viviparity means to give birth to young who develop inside the body of the mother rather than hatching from eggs. Mammals are viviparous and birds are oviparous. Therefore, option C is the characteristic that is present only in mammals but not in birds.
- Both mammals and birds are warm blooded. Therefore, option D is the characteristic that is present in both mammals and birds.

Thus, the correct answer is option C Viviparity.

Note: Some other characteristics that are not shared by birds and mammals are that birds have toothless beaks, and feathers and mammals are known as endothermic organisms.