試題詳解

44 Which of the following could be considered the most recent common ancestor of living tetrapods?
(A)a sturdy-finned, shallow-water lobe-fin whose appendages had skeletal supports similar to those of terrestrial vertebrates
(B)an armored, jawed placoderm with two pairs of appendages
(C) an early ray-finned fish that developed bony skeletal supports in its paired fins
(D) a salamander that had legs supported by a bony skeleton but moved with the side-to-side bending typical of fishes