Which of these might have been observed in the common ancestor of chondrichthyans and osteichthyans?

Question

Quizplus · Accepted Answer

The common ancestor of chondrichthyans (cartilaginous fishes like sharks and rays) and osteichthyans (bony fishes) likely had a mineralized, bony skeleton. This feature is observed in early fossils of both groups, indicating its presence before their evolutionary paths diverged. Limbs and digits are characteristics that evolved later in tetrapods, and the swim bladder is a feature specific to certain osteichthyans, not present in the common ancestor of both groups.

Which of These Might Have Been Observed in the Common