Reptiles are the first group of animals to lay eggs on land. The
major adaptations occured to solve the problem of water and new
environment.
Various adaptations which allowed reptiles to move farther
inland are :
- Reptiles lay egg filled with amniotic fluid, and egg is
protected by a hard external covering . This allowed repltiles to
lay eggs on land.
- Development of thick and tough outer skin with keratin and
presence of scales. The thick skin allows for moisture storage and
keratin provides protection.
- Release of concentrated urine (efficient kidneys ).
- Development of lungs for breathing on land.
- Reptiles are cold blooded , and they adapted to sun basking
which helps to elevate internal body temperature for normal
functioning .