The earliest vertebrates were
a. bony fishes.
b. spiny fishes with skeletons of cartilage
c. amphibians with thin, moist skin
d. jawless fishes
Answer: d
Biology Questions and Answers.
a. bony fishes.
b. spiny fishes with skeletons of cartilage
c. amphibians with thin, moist skin
d. jawless fishes
Answer: d