Which of the following is evidence that dolphins evolved from four legged mammals not fish

-The structure of their body contains two small pelvic bones that are rod shaped which considered as vestigial legs that turned into turned into flippers.

- Unlike other fish, dolphin breathing mechanism utitilize lungs just like the mammals on land does.

- They also developed breast to give food for their infants

Dolphins are technically mammals, because they have blow holes instead of gills to breath, coming to the surface for air. Their bone structure as well more closely resembles land mammals rather than fish, with dolphin's spines moving vertically while a typical fish spine moves horizontally.