The consensus is that the coelacanths and lungfishes (Sarcopterygii) represent an evolutionary link between ray-finned fishes and tetrapods. What is the major feature in the Sarcopterygii that supports this hypothesis?

Choana, paired fins with a fleshy base over a bony skeleton, persisting notochord, 2 dorsal fins and nares.

Explanation:

Sarcopterygii also known as lobe-finned fishes which usually possess a choana, paired fins with a fleshy base over a bony skeleton, persisting notochord, 2 dorsal fins and nares are present internally. The lungfishes are considered the closest living relatives of tetrapods because of the presence of some common features. The African lungfish has epithelial crypts located at the base of the lamellae of the olfactory epithelium that express markers of the vomeronasal receptors in tetrapods.