Air breathing, four-footed, ambling amphibians leave many marks by the late Devonian Period. Their ancestors — the lobe-fin fishes — were most likely lured out of the oceans by a profusion of insects.
Evolving to breathe in air was not the only challenge faced by lobe-finned fish in their move to land. They also had to support their weight against gravity. The bony skeletons of amphibian precursors (who lobbed about on already-muscular fins) give clear clues to the transition some animals made from dragging in drying mud-pools to true walking movements.
Amphibians do not make a complete land transition: they must return home to lay eggs, where their tadpole progeny keep one evolutionary foot in the water.