Explanation

Nearly a century ago, T H Huxley called birds ‘glorified reptiles’ thereby meaning that birds have evolved from some reptilian ancestor. Both the birds and reptiles lay the same type of eggs, which are deposited outside water. Eggs are large and telolecithal. The ovum is surrounded by albumen, an egg membrane and a thick hard calcareous shell,which are all secreted by special gland located in the walls of oviduct.