Cartilaginous fishes, such as sharks and rays, indeed lost the heavy dermal armor of their ancestors, evolved from ancestors with bone to an all-cartilage skeleton, flourished during the Devonian and Carboniferous periods but nearly went extinct at the end of the Paleozoic era, and lack a swim bladder, which is a characteristic feature of bony fishes for buoyancy control.

Solved

Cartilaginous Fishes

Question 18

Multiple Choice

Cartilaginous fishes

A) lost the heavy dermal armor of their ancestors.
B) had ancestors with bone but moved to an all cartilage skeleton.
C) flourished in the Devonian and Carboniferous but nearly went extinct at the end of the Paleozoic.
D) lack a swim bladder.
E) All of the choices are correct

Correct Answer: