Question

During early stages of development, dolphin embryos begin to develop hind limbs. By the time the dolphin fetuses are fully developed, the hind limbs have disappeared.

Which statement best explains the early development and then disappearance of hind limbs in dolphins?
A.Dolphin fetuses change their development to adapt to an aquatic environment
B.The genes that control the development of hind limbs are destroyed as the fetus develops
C.The early ancestors of dolphins had hind limbs
D.Dolphins are evolving to become terrestrial animals.

Answer 1

C. The early ancestors of dolphins had hind limbs.

Explanation: Embryonic development often reflects evolutionary history. Dolphin embryos briefly form hind limb buds because their ancestors were terrestrial mammals with hind limbs; later in development those limb structures are suppressed/removed (not that genes are destroyed), resulting in the adult whale/dolphin body plan.