Bony fish divide in two
The lineage splits into ray-finned and lobe-finned fish — and one branch will walk.
- When
- Known to
- ± 5 million years
- Era
- Silurian, Paleozoic
Osteichthyes, the bony fish, diverge into the ray-finned actinopterygians and the lobe-finned sarcopterygians. Ray-fins become the overwhelming majority of fish alive today, some 30,000 species. Lobe-fins, with fleshy limb-like fins containing a single proximal bone, remain a minor group — but they include the ancestors of every four-limbed animal that has ever lived, humans among them.