Eggs of reptiles, birds, and a few primitive mammals are laid on land, usually away from water and sources of food. what features of land eggs such as those found in birds allw this typeo f early development?
Amniotic sac allows the fetus to be surrounded by water and therefore, the temperature is more stable. This type of eggs is a synapomorphy of the amniotic group conformed of reptiles, birds, and mammals. There's also a nutrient component so when the baby comes out it will have enough energy to find a source of nutrients by itself.
