How does ontogeny recapitulates phylogeny relate to evolution?

Ontogeny Repeats Phylogeny also called Recapitulation theory states that the devlopemental history of an organism repeats it's ancestral characters. eg - The larva of frog that is Tadpole has tails and respire with gills , it represents that amphibians evolved from Fishes. eg - Human embryo has initially 2 chambered heart like fishes , then 3 chambered heart like amphibians , then 3 1/2 like Reptiles and finally 4 chambered heart , it shows our evolution from fishes , amphibians , reptiles.