All of these might have been observed in the common ancestor of chondrichthyans and osteichthyans, except
A)a mineralized, bony skeleton.
B)scales.
C)lungs.
D)gills.
E)a swim bladder.

Question

Quizplus · Accepted Answer

The swim bladder is a specialized gas-filled organ found only in some bony fish, it is not present in cartilaginous fish (chondrichthyans). Therefore, it could not have been observed in the common ancestor of chondrichthyans and osteichthyans. A, B, C, and D are all features that are present in both chondrichthyans and osteichthyans.

All of These Might Have Been Observed in the Common