Final answer:
Amphibians were the first four-legged animals to reach land. They had to develop adaptations to breathe air and move on land.
Step-by-step explanation:
The first four-legged animals to reach land were classified as amphibians.
These early amphibians were the first vertebrates to move to land from water.
They had to develop adaptations such as the ability to breathe air instead of obtaining oxygen from water and the ability to move around well on land.
Amphibians include animals like frogs, salamanders, and caecilians.