Amphibians

Lured To Land

395 MYA

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.

Fish, evolving into amphibians, were the first vertebrates (the group of animals with backbones, to which human beings belong) to make it to land. (Illustration by Zdenek Burian, © Jiri Hochman and Martin Hochman)

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