The first sharks
Cartilaginous fish appear and begin a lineage that outlives almost everything around it.
- When
- Known to
- ± 10 million years
- Era
- Devonian, Paleozoic
Chondrichthyans — sharks and their relatives — diversify through the Devonian, with skeletons of cartilage rather than bone and teeth replaced continuously throughout life. Their teeth, being mineralised, dominate the fossil record while their bodies rarely survive. The group persists essentially unchanged in basic design for over 400 million years, through every subsequent mass extinction.