Tetrapod
Tetrapods adapted to terrestrial environments over time and spent longer periods away from the water. They also spent more of their juvenile stage on land before returning to the water for the rest of their life. It is also possible that the adults started to spend some time on land  to bask in the sun, close to the water's edge. The first true tetrapods that were adapted to moving on land were small. Only later did they increase in size.