Lobe-finned fishes of the vertebrate class Sarcopterygii migrated out of fresh water and adapted to life on land and further amphibians were evolved from such fishes.
What are lobe finned fishes?
Coelacanths, lungfishes, tetrapods, and their extinct ancestors, such as the osteolepiformes and panderichthyids, belong to the Sarcopterygii, or lobe-finned fishes.
Together with ray-finned fishes (Actinopterygii), they make up the bony fishes (Osteichthyes).
The fleshy pectoral and pelvic (paired) fins of sarcopterygians connect to the pectoral (shoulder) and pelvic (hip) girdles by a single bone.
The coelacanths and lungfishes, which resemble fish more naturally, are examples of this. With the single bones standing in for the humerus (forelimb) and femur, these lobe-fins gave rise to the paired limbs of tetrapods (hindlimb).
