Evolution and success of fishes
According to fossil records, the most primitive fishes which first acquired vertebrae appeared in the Early Cambrian Period (about 530 million years ago). At the beginning, fishes did not have jaws, but when they acquired jaws, fishes rapidly diversified. In the Devonian Period, not only all major taxonomic branches of fishes but also amphibians appeared. In the process of the evolution, fishes have developed jaws, skeletons of limbs, lungs which made possible descendants to live terrestrial life.