The ancestors of all these groups were terrestrial, with open tracheal systems, convergently evolving different types of gills for their aquatic larvae as they took to the water to avoid predation.
Os antepasados de todos estes grupos eran terrestres, con sistemas traqueais abertos, nos que por evolución converxente apareceron diferentes tipos de branquias nas súas larvas acuáticas a medida que adoptaron o medio acuático para evitar a depredación.