They are vertebrate, which mean that the have a backbone, allowing them to grow larger than invertebrates. They also have more possible brain growth because of this. They have scaly skin and lay eggs. Reptilia, known commonly as reptiles, are able to live completely on land in part because they lay water-tight eggs and internal fertilization. Most reptiles are also camoflauged, and have a simmilar bone structure as birds.
Reptiles can also live on land because their leg positioning allows for more support.
Also, reptile's organs are more efficient than those of amphibians because of changes to the heart and lungs. I have a long, scaly tail. I have eyes on the sides of my head. I have sharp teeth. I am cold blooded.