When early systematists distinguished chondrichthyes (cartilaginous fish) from osteichthyes (bony fish), it was not clear exactly when bony skeletons first appeared in the vertebrates. which of these suggests that a reduction of bone in chondrichthyes is a derived condition that emerged after the origin of bony skeletons? a) all fish except agnatha have jaws.
b) chondrichthyes and osteichthyes have paired fins and lateral lines. c) traces of bone tissue are found in living and fossil chondrichthyes. d) the cartilage skeleton of chondrichthyes is impregnated with calcium.