Question

Which one of the following characteristics of birds indicates the reptilian ancestry?

• A. Two special chambers, cro and gizzard in their digestive tract
• B. Eggs with a calcareous shell
• C. Scales on their hind limbs
• D. Four-chambered heart

Answer 1

Answer: (B)

Eggs with a calcareous shell

Birds and reptiles have many similarities. The reproductive similarity includes the oviparity, in which the egg is laid by the organism for the external development of the young ones. Both the birds and reptiles make eggs coated with calcium shells. This is done to prevent the entry of water into the egg. In order to make the calcareous eggs, both the birds and reptiles show internal fertilization. Since, calcareous eggs appeared first in reptiles, birds are often assumed to have reptilian ancestry.

Hence, the correct answer is 'Eggs with a calcareous shell'.