The First Vertebrates

What happened

The first vertebrates — small, jawless fish — appeared in the ancient oceans. Over the following tens of millions of years, fish diversified spectacularly, evolving jaws and bony skeletons and coming to dominate the seas during the Devonian 'Age of Fishes.'

Why it matters

Vertebrates — animals with backbones — include every fish, amphibian, reptile, bird, and mammal that would ever live, humans among them.

Sources

• Smithsonian Ocean, National Museum of Natural History. Ocean Through Time · Reputable source