Question

Which of these characteristics first developed in reptiles? amniotic egg four-legged body animals with lungs. skull and vertebral column scales on skin?

Answer 1

Am amniotic egg is first developed in the reptiles. 
The membrane and shell make a protective membrane that can provide a safe environment for the cells to divide, and embryo to develop. Animals having an amniotic shell are called as amniotes. The other body parts develop later on.