What aromorphoses in the structure of the integument, respiratory and circulatory systems occurred in reptiles?

1) Dry skin and horny formations on it prevent the evaporation of water from the body (the disappearance of skin respiration), which contributed to the spread in the ground-air environment.
2) Cellular lungs increased the area of gas exchange and the flow of oxygen into the blood, which increased metabolism
3) The appearance of an incomplete septum in the ventricle of the heart reduced the miscibility of blood, ensured a more efficient supply of oxygen to organs, which increased metabolism