The fossil evidence proves this. The extinct Coelacanth and Rhipidistian were the fish that evolved into the amphibians. Dipnoi is the immediate ancestor of the amphibians.
Fish evolved from simple organisms in the oceans. Fish eventually evolved lungs and then evolved into amphibians.
The Facts Are .....
The rhipidistian fossil fish could not be the ones that evolved into amphibians. A close examination of rhipidistian and amphibian fossils show that there are enormous differences between them. Michael Denton, "Evolution: A Theory in Crisis", Burnett Books: London, 1985 p:180
Some scientists have dismissed the lungfish Dipnoi as the immediate ancestor of amphibians because its fins would have been too weak to become legs. Its skull is said to be too unlike an amphibians to have turned into it. The evolution of amphibians is not a fact, only a guess. Arthur C.
Echternacht, "How Reptiles and Amphibians Live", Galley Press: Leicester (England), 1977 p:27
Before the discovery of the coelacanth (a Crossopterygian fish), their fossil predecessors were held to be the evolutionary link between fish and amphibians. An examination of these living fish showed that there was no evidence that their internal organs were being adapted for use on land. They are no longer referred to as missing links. Nature, December 22/29, 1988 p:727-732; National Geographic, January, 1989; "World Book Encyclopedia", (Vol. 4), World Book Inc: Chicago, 1984 p:602; Michael Denton, "Evolution: A Theory in Crisis", Burnett Books: London, 1985 p:178-179
Lungs in fish are not a modern evolutionary development as there is evidence that the most
'ancient' fish already had functioning lungs (eg Placodermi sp). Romer & Parsons, "The Vertebrate Body", Philadelphia: Saunders Co., 1978 p:329
"Since the fossil material provides no evidence of other aspects of the transformation from fish to tetrapod, paleontologists have had to speculate how legs and aerial breathing evolved ....." Written by Barbara J. Stahl (St Anselm's College, USA) in her book "Vertebrate History: Problems in Evolution", McGraw-Hill: New York, 1974 p:195
"The origin of all these fishes is obscure ..... It is not possible to demonstrate unequivocally the descent of any group of the higher fishes from a specific stock of placoderms or acanthodians." Written by evolutionist and vertebrate specialist Professor Barbara Stahl in her book "Vertebrate History: Problems in Evolution", Dover Publications: New York, 1985 p:126
"There are no intermediate forms between finned and limbed creatures in the fossil collections of the world". Written by the famous science writer Gordon Rattray Taylor in his book "The Great Evolution Mystery", Harper & Row: New York, 1983
"..... none of the known fishes is thought to be directly ancestral to the earliest land vertebrates."
Written by Barbara J. Stahl (St Anselm's College, USA) in her book "Vertebrate History: Problems in Evolution", McGraw-Hill: New York, 1974 p:148
"The geological record has so far provided no evidence as to the origin of the fishes ....." Written by zoologist and evolutionist J.R. Norman (Assistant Keeper of the Department of Zoology, British Museum of Natural History) in his section "Classification and Pedigrees: Fossils" of P.H. Greenwood's book "A History of Fishes" (3rd. ed.), Museum of Natural History: London, 1975 p:343