Most fish species today, and those found in the fossil record, have skeletons made of bone, not cartilage,
and belong to the fish group Osteichthyes. Devonian times saw a major grou:p of these fish, known as
lobe-fins, or sarcopterygians. Lobe-fins include lungfish and coelacantbs, and also long-extinct fish
closely related to the ancestors of tetrapods -" amphibians and other four-legged vertebrates.