The group that includes lobed-finned fishes is which?

The group that includes lobed-finned fishes is which?

• A. Sacropterygii
• B. Actinopterygii
• C. Amphibia
• D. Mammalia

Answer: (A)

Lobe-finned fishes belong to Sarcopterygii, a group defined by fleshy, lobed fins with internal bones that resemble limb bones. This fin structure signals their evolutionary connection to land-dwelling vertebrates, and living members include lungfishes and coelacanths. In contrast, ray-finned fishes (Actinopterygii) have fins supported by slender rays rather than a robust internal bone pattern. Amphibia and Mammalia are tetrapods, not fishes, so they don’t represent the group that includes lobed-finned fishes.

Lobe-finned fishes belong to Sarcopterygii, a group defined by fleshy, lobed fins with internal bones that resemble limb bones. This fin structure signals their evolutionary connection to land-dwelling vertebrates, and living members include lungfishes and coelacanths. In contrast, ray-finned fishes (Actinopterygii) have fins supported by slender rays rather than a robust internal bone pattern. Amphibia and Mammalia are tetrapods, not fishes, so they don’t represent the group that includes lobed-finned fishes.